It was too cold for Greg's taste. He didn't like the winter, the dry skin, nose bleeds, the chill in his bones, hot ceilings, cold floors, the moisture of the winter rains and melting snow at his feet that never seemed to dry out, the cabin fever. Greg was a summer animal, enjoying the basking heat and skimpy clothes. And with each autumn, Greg turned miserable. He rang the door bell and shivered. He blew into his hands to warm them.
     Jennifer answered the door and smiled. "Well, I'm glad you could make it. Come on in and get warm."
     "Thanks." He wiped his shoes on the door mat and walked inside.
     "Let me take your coat. John is in the den working on his money collection."
     "Money collection?" he inquired.
     "Mmm-huh. I'll let him explain it. After all, it's his hobby."
     Greg wandered back through the house and found John working with a picture frame. He cleared his voice to announce himself.
     "Oh, Greg. Have a seat. I'll be finished in just a moment."
     "What are you mounting?"
     "Money."
     "Art riche'?"
     "Well, actually, it's not the money per se. It's money that people have written on. Little puzzles of the mind. Sort of like a friend I knew who used to photograph graffiti. I collect bills that have messages on them. They pose little puzzles to solve."
     "Such as?" Greg queried.
     "Well, such as this twenty. 'Mr. Too Sweet.' I see two couples in a restaurant. One couple is established, and the other is a blind date or a couple that has just started dating. The women are sitting side by side, as are the men. The check has been delivered and one of the men has placed a twenty, possibly other bills on the tray. The woman in the established relationship gives some sort of signal to the other, possibly mouths the words silently, asking what she thinks of the man she's dating. She reaches over to the man and pulls a pen from his pocket and starts doodling on the paper napkin. She finds that the pen tears the napkin when she tries to write, so she writes on the money, 'Mr. Too Sweet.' There are obvious suspicions that the man is wearing a mask hiding darker feelings, paying her too much romantic attention. He's obviously on the prowl. It doesn't look like they'll be together much longer. She covers the bill with the check so the men can't see what she's written."
     "You get all this from that one message?" asked Greg.
     "Well, it's how I see it happening. People don't generally write on money when there is paper handy. Not enough free space to write a lot. So for people to write on money, they have to be desperate for paper. I see phone numbers most often, people calling information from a pay phone or from some public phone where the phone book is absent. And there are the usual four letter words by juveniles. Most of them are pulled by the banks. And there are also the bundled bills with the total amount on the top bill, and sometimes there's a little math being figured. And there's also names, usually of someone that's the target of someone's infatuation. All those I don't keep. There's no puzzle in them. I look for ones where there is a sense of communication." John explained.
     "Oh, and you are mounting those."
     "Yes. The good ones don't come along everyday. Maybe a couple a year will find their way into the store's cash register. Sometimes more often, but the mean average is one every five or six months. I keep a couple of each denomination in a little fold in my wallet and swap them out whenever I find a good one to keep the tally correct."
     "What are some of your other ones?"
     "Well, this was one of my favorites. 'NO!' That one has given me many stories. A wife telling a husband to change his mind on an offer she wants no part of sharing. A boss telling an employee that he has grossly overstepped his bounds. Any number of possibilities where someone opened his or her mouth without consultation. But it was so wide open that it never lent itself to details of the situation. Too many possibilities, too vague. So does 'Stop that.'
     "I tend to like the larger denominations. They're more telling. Ones and fives are pretty much in the hands of everyone, so it doesn't delineate the atmosphere. It could be kids or adults, rich or poor people, and they could be used anywhere. The larger denominations tend to be for payment of more expensive items, such as group dinners and work oriented payments, or at least high dollar items. But your messages fall into two prominent categories, memos and secretive communications. There are a few minor ones, such as political sentiment, 'viva somebody' or 'somebody is a louse'. And there will be an occasional poem, usually a limerick.
     "This one is my current favorite. 'Tell Dad there's gravy on his tie.' It speaks of familial embarrassment. One is not favored and doesn't dare tell him something like this, but is socially proper enough to not want to be further chagrined by association. The reader obviously has his father's ear in a more favorable light, not the one to be blamed as often. It's obviously a social gathering, probably a family reunion or such. That it's on a fifty makes it even more revealing, noting that it's a family of some prominence in all likelihood, and that the affair is at a place of some elegance. I can just see the disgust and shame the author felt. So proper, but not to the point that he is called Father."
     "You are just guessing, though." Greg inferred.
     "Oh, of course. It's all open to interpretation and imagination, at least the good ones are. 'Sit up straight.' has as many variations as well. This one is a typical example. 'Rita is a whore, you idiot.' I can see a high priced call girl being mistaken for a woman of prominence and being treated as such by someone. Or it could be something else, a jealous woman at a beer party, since it's on a five. She may not actually be a prostitute, she just may be someone in disfavor and considered such. Each message has many possibilities, and it is for the reader to ponder over them until they fit in a way that pleases them. Stimulus for the imagination. The reason I'm mounting these bills for display is to get the input from others, to open discussion. Here, tell me what you think this one could be. 'Larry did it again."'
     "Well, that would all center on what 'it' is. Obviously a shunned habit or a tendency for a mistake, probably social, though not necessarily."
     "Go on."
     "You want me to list what I see as possibilities?" asked Greg.
     "Yes."
     "Well, I don't see it as embarrassing. To me, it reads more toward annoying. Talked to someone he shouldn't have, such as a pretty woman, or spilled his drink, or wore the wrong clothing style, or made a speech and said something out of form, but not bringing that much public disgust. I think it would have read 'blew it' instead of 'did it' if that had been the case. So it's more of a private contention, a problem seen by a couple of people, but not overall considered faux pas. Maybe he got up and sang when he has a less than ideal voice, or he sang off key. It's too wide open to pin down, but it was written that way to keep detection down, in case someone for whom it wasn't intended happened to see it. This adds to the case of a private annoyance."
     "How about this one? 'He's all yours."'
     "Two women man-watching in a bar. The author has no interest in the man mentioned. She might know him, or it might be based upon impression. Pretty simple. I don't see it as one woman surrendering a man to another woman. That would be expressed in another manner, not written on money."
     "You don't think so?" John asked.
     "Not if the degrading relationship was for any length of time, say more than an hour or two. It might be for a lengthy relationship if it was just a doodle, but not as a message."
     "How about this? She owes the new woman a small amount of money, say borrowed cab fare or something similar. She doesn't want to tell her this message to her face, so she writes it on the bill so she'd see it later."
     "No, it would be signed."
     "Not if it was on the top bill where she saw it right away."
     "No. Not likely, because of the circulation of money goes through too many hands. It would be on a note, not on a bill."
     "Unless it was done, say, in the bathroom. She took her purse in with her, wrote it, rolled up the bills with it on top, and hands it to her when she comes out and leaves." John posed.
     "Possibly, but I don't see that. I see a bar, money for the tab is on the counter, waiting for the bartender's attention. Maybe it's the script, or that it's up in the corner on the border, but I get that impression. If it had been as you said, it would have been written more boldly where she would be sure to notice it, probably across Washington's face. This was probably seen being written."
     "You have a point there. But maybe it was done that way so she'd see it in her wallet as she flipped through the bills in paying for something."
     "But you can put bills in four different ways, face forward and upside down, and only one of those ways would reveal it."
     "Okay, point taken. How about 'Greasy, sleazy, wheezy'?"
     "Three of the seven dwarves?"
     John laughed in response.
     "Probably another date opinion, like 'Mr. Too Sweet', but an immediate turn-off. But it could be something business related. A salesman, perhaps, probably relating to real estate." Greg offered.
     "I like that. I never thought of it that way. Tell me, what do make out of this? It's the only math I ever kept, and that's because I never have been able to figure it out. You're good at math."
     "Calculus. A trigonometric integration. It doesn't ring a bell, though. Nothing that I learned as a standard equation. I could copy it down and give it some study if you like. With a little research, I might even be able to tell you to what subject it covers."
     "Do you think so?"
     "Yes. There's ample use of the Greek alphabet as variables. Offhand, I'd say physics, from the combination in the function as written. Probably quantum mechanics."
     "A modern day 'Eureka'?" asked John.
     "Perhaps, but it could be industrial espionage as easily. Not to say that it is. Don't jump the gun on me. Let me study some reference material and get back to you on it first."
     "Okay. How about this one? 'Silicone valley'?" John offered.
     "Probably talking about implants and cleavage. The author probably knew her before the operation."
     "Now why didn't I think of that? That is a spicy one, and here I was thinking electronics. I'm glad I showed you that one. That opens the imagination to all sorts of possibilities."

     Greg worked on the formula for four days in his spare time and got nowhere. He pinned down that it was related to time, strong nuclear forces, and wavelength, but that was as far as he could take it. It was nothing that he could find in standard theory. He wasn't able to delineate the function in the equation. It seemed to be a base product and not subject to derivation, and the oddest thing was that time was the prime of the function and not a variable as it usually was in such equations. He consulted every reference he had on quantum mechanics and found nothing that would shine additional light on the subject. He found nothing more at the library.
     He realized his biggest problem was that he didn't know an application for the odd formula, and that he was trying to work backwards. Instead of working from theory to application, he was trying to deduce the theory with only the math, and he suspected that it was only part of the total theory that was represented in the equation.
     He gave up studying it when he had found nothing new after hours of study. He went back over to Greg's and explained what he had inferred, and the matter was dropped.

     It was late spring when Greg was asked to go fishing with Charles, a dyed-in-the-wool serious angler who thought of nothing else. The man spent thousands on his hobby each year, but he wasn't just a slave to the market. The man knew fish like few people did, their food chain, behavior, diseases, and just about everything else. By looking at fish, he could tell a person what the fish had been eating, what its diet lacked, its age and gender, and more. Greg always considered a day-long trip out on the water with Charles as an educational experience, and he was always eager to listen. He also enjoyed the fish he brought home for the table, which was never all he caught that day. Charles believed in a program of keeping some of the fish in a certain size range and releasing the others, especially the larger ones, to ensure balance in the fish population of the lake.
     They finished the day with the sun low in the sky. Greg felt tired from the day of activity, but it was a well-satisfied tired. He had crappie and white bass swimming in the live well, along with one eleven pound white bass/striped bass hybrid that Charles called 'wipers' for their ability to destroy reels that were not heavy enough for their size and power.
     They had trailered the boat and decided to go for a bite to eat before heading back to town. They decided on a restaurant that Charles frequented at the end of a day of fishing. The food wasn't too heavy, but it satisfied the body of the nutrients spent in the rigors of a full day out. Everyone that worked there knew Charles and treated him with the preference given to a loyal customer and friend. They talked more about fishing, a topic on which Charles could never be exhausted.
     Greg insisted on paying for the meal. In the past, the two had fought over the check. But Charles allowed Greg the honor, knowing that if he didn't, he'd find the price of the meal tucked in one of his tackle boxes when he got home. Greg had gotten in the habit of peeking in cash register drawers, looking for bills that had writing on them, scouting for new material for John's collection. He spotted a five that had words on it, but the writing was upside down from where he stood.
     "Excuse me. Before you close the drawer, I'd like to get one of the bills you have there. I'll pay for it. I'm not robbing you. I have this friend that collects money that has writing on it. I know it's an unusual hobby, but he has a certain flair of using his imagination to try and figure out the circumstances for which the writing was done. So I collect them for him when I run across them. Would you mind?"
     "No. This one?" the waitress responded.
     "Yes, the five." He pulled a ten out of his pocket and gave it to her. She handed him the five and another one as change. He read the words 'Powerful gasoline, a clean windshield, and a shoe shine'. Greg chuckled, remembering it as a quote from an album that had been popular several decades before, indicating absurd religious and political beliefs.
     "I think I have another one if you'd be interested." she offered.
     "Sure, if it's interesting enough."
     "Well, it's weird. I don't know if you'd call it interesting."
     She pulled out a twenty, and Greg saw another integration formula on it. He reached quickly for his wallet and pulled out a twenty and the exchange was made. He stood there looking over the equation.
     "Do you understand that stuff?" asked the bewildered waitress.
     "I studied calculus in college. It makes a little sense to me, but I'll need to think it through to figure out what it means exactly."
     "Well, I was lucky to finish algebra." she offered.
     "No small feat in itself." he complimented, and the waitress smiled. He left her a thirty per cent tip, and she smiled even wider.

     Greg spent the next full day going over the equation. It was in the same writing as the other one had been when he checked it over with John the night before. He'd gone over with the bills immediately after cleaning the fish he kept and bathing to get the smell of the fish off of him. John paid him for the two bills, and they had discussed the formulas.
     The second equation was considerably more complex, dealing not with quantum mechanics, but with vectorial analysis. The variables were time, distance, velocity, angles, and linear and angular acceleration and there were seven stages in the equation. He found time to be the independent variable from the list of values on the opposite side of the bill. Here he had better luck in finding the theory.
     Within the day, he had deduced the meaning. It was a formula for determining the displacement of any given location on Earth over time in reference to the universe. It dealt with galactic velocity in the expanding universe, rotational angular velocity of the galactic arms, revolution of Earth around the sun, and rotation of the Earth, along with orbital decay of the sun and the Earth, the perturbations of the sun with the neighborhood of local stars, and the placement of longitude and latitude and altitude above sea level.
     It was a masterpiece in itself, but it still puzzled Greg what it had to do with the other equation. It had to be the fact that time was the independent variable. Time was the key again. He returned to the first equation with this particular in mind. How the displacement of the Earth relative to the universe related to the first equation was the essential key to comprehending its meaning. But time was the object of the function, not a variable, in the equation.
     A thought hit Greg, and a twisted smile formed on his face. "No. It couldn't be. That's a pipe dream." But then the smile turned down on his face as he looked at the first equation.

     Greg looked at the name Desmond Renfro on the frosted glass door. He swallowed and sighed and opened it. He found a lobby, but no secretary was sitting at the desk that should have held one. He went over to the inner door and knocked. He heard noises, then the door opened. There was a man with graying temples and a balding crown. "Yes?"
     "Professor Renfro, I'm Greg Thomas. I called."
     "Oh, yes. You're the one with the problem."
     "Yes. I was once a student of yours. I'm not sure if you remember me. I have a couple of equations that I'd like to discuss with you."
     "Okay, but I don't have a lot of time. I have a departmental meeting in fifteen minutes."
     "Well, it won't that long to present them to you, but it may take considerably longer to resolve them. But you won't need me for that."
     "Come in and sit down." Greg went in and sat in the offered chair. "Now what is the problem?" Renfro inquired.
     "Well,it started with a friend that collects money."
     "A coin collector?"
     "No, he collects paper money, but not for the monetary value or its rarity. He collects money with things people have written on the bills. It would take some time to explain properly, but he plays with the things written to imagine the situation under which these things were written. A psychological game."
     "Then you want the psychology department, not me. I deal in physics."
     "Allow me to finish, please. He had found an equation on one of these bills that puzzled me for some time. It was a proper equation, but it just didn't make sense to me, not until several months later when I ran across a second bill with the same ink and handwriting. It was a much different equation. First let me offer you that one." Greg reached into a folder and handed him a computer printout. "To make things short, I determined that this is an equation for vectorial determination of displacement of any spot on the Earth's surface in relationship to the universe. With a little study, I think you will concur. The first is galactic expansion, the second is galactic spin of the arms, the third is decay of that orbit, the fourth is local gravitational perturbation, the fifth is Earth revolution, the sixth is orbital decay, the seventh is Earth's rotation, adjusted for longitude, latitude and elevation above sea level."
     "Possibly."
     "I don't expect you to accept my word without enough study on your part to verify this. But as you can see, it's all fairly simple mechanics in the Newtonian system, mks. It took a little while for me to determine this, but I am reasonably sure that that is what it represents. I had a couple of courses on astrophysics, and that is what led me to identify it as such." Greg explained.
     "Well, this is a compilation that deserves merit, if it is that, and you are to be congratulated. But I don't see the point."
     "Let me remind you that I wasn't the author. I found this on a twenty dollar bill. I only determined its purpose. And the point is the first equation that I ran across." Greg again reached into the folder he held and presented Dr. Renfro with the other sheet of paper.
     "What is this?"
     "You tell me. I have an idea, but you'd think that I was crazy. I'm not so sure about that myself at this point. It's why I came to you."
     "It doesn't seem to make much sense. Why is time the object of the function?" Renfro asked.
     "Like I said, it puzzled me to no end until I started relating it to the other equation. I'm not convinced myself that it isn't some elaborate practical joke, but it seems highly unlikely to me, having gotten into the psychology of writing on money. Before you give that further thought, let me say a few things on the way I see this. Mind you that this is purely speculation, so bear with me.
     "First, let me say that I suspect that there might be other equations that belong in this set, and that this is only two of a set written by one man on a theory he envisioned. Theory is relatively simple to remember if you have the math written down. For some reason, this man wanted to preserve the math of this theory, but he was in a situation where he no other paper in his possession upon which to write. There are a number of possibilities as to why. He may have been held by governmental authorities, or he may have been somewhere off in the countryside, or even something else could be the reason.
     "Whatever the reason, be it his money was his only paper, or perhaps something more a bit complex, like it was the only way he could insure that somebody else might see his ideas, he wrote the math to his theory down so that he wouldn't forget it. If I do see the theory that he had envisioned, it could be very dangerous to know it in the eyes of the authorities. I've yet to hear that such ideas have been discovered. So do be careful with whom you speak over this matter.
     "I know I'm sounding a bit, if not more than a bit, deluded. But give the equation some thought, and think about the implications that have been expressed in popular fiction. It's full of paradox and uncertainty, enough to scare those in power into being quite rash if it were to become true."
     "Wait. Are you trying to tell me that this is an equation for time travel?" Renfro asked, chuckling.
     "I'm not trying to do anything but present the equation to you and let you draw your own conclusions. But that is what I see in the equation. Why else would there be concern about displacement of the Earth in relation to the universe with time as the independent variable in one equation and have the object of the function of time in the second?"
     "Is this a joke?"
     "I'm not joking. Maybe the person who wrote this on the bills is, but if he is, he went to an awful lot of trouble over a joke. There may be other equations involved that I haven't seen, but the short one seems to be the prime equation. And let me note that my studies show that it can't be derived. But I feel that if it holds water, the missing, if any, equations can be deduced from analysis. But we're getting ahead of ourselves. I'm not sure if the equation holds water. It's a little over my head in theory. That is why I came to you.
     "What I'm asking of you is to give it some private study and see what you think. For now, let's just keep this between us. If you concur with my ideas, then we need to find a way to present the ideas and any possible correlations to the scientific community as a whole without first tipping our hand to the government, if we decide that it should be pursued further. I'm not yet convinced that it is knowledge fit for the human race to hold. Can I count on your secrecy?"
     "Yes. I understand your point. I've seen research capped before by the government. I have no desire to go that route myself. I have to make that meeting. I'll get in touch with you. I'll need your phone number."
     "Best not to use the phone system. I'll give you my phone number and address. Let's keep communications in person unless there is an emergency."
     "Not a bad idea."
     Greg handed him a card with his name, address, and phone number. "I have an answering machine. Use the name Billy for safety, and be a little vague or cryptic. Things like 'Finally got it fixed' or the like. If word on this does get out, I'd prefer that we both be hard to pin down. Also, watch the names of any computer files, and keep the theory in your head. Also plant any material in hands that you can trust not to peek. Computer files with someone that doesn't have access to the same sort of computer and programs. I don't mind admitting that the idea of this being true scares me. I'm rather hoping to see the equation turn out to be a meaningless scribble."

     Greg arrived home, his nerves not setting well on his stomach. He sat at the kitchen table, not in the mood to eat, but feeling that he needed something on his stomach. He was about to get up and fix something, when a blurred spot appeared in the center of the table. There was a loud pop, and in the place of the blur sat an envelope. He reached over and touched it as if it were a rattlesnake. Nothing happened, so he picked it up and opened it. He unfolded the contained piece of paper and read.
     "Dear Greg, this is just to keep you from falling apart and calm your fears. Your hunch was right. It took some work, and the road was not altogether smooth, but there were not the disasters that you anticipated, thanks to some sly prestidigitation. I won't give you the details for obvious reasons that were discussed.
     "I just want to say thanks for showing me your ideas, and it turned out to be safer than expected. We can't seem to get animals to go through the maze and come out alive. But other than that, it works like a dream. I hope that you are ready for a career change. I can promise you excitement and a few headaches along the way, as well a chance to meet the author. You were right on the money about why he used cash as paper. You'll like him, I guarantee. The proof is in the pudding.
     "Do burn this letter and feel at ease. Buy yourself some rose-colored glasses. Lawyers are great friends in times of need. Keep the faith."
     The letter was signed Billy and dated fifteen years in the future. Greg chuckled, and his mirth grew to an uproarious laugh that drained him of all his nervousness and left him a touch weak and lightheaded. He burned the letter. The he went to his writing desk and retrieved a pen. He took out a ten dollar bill and wrote, "The future is in your past. Enjoy." He took the bill over to John and offered it to him for his collection.