boza. A woman sitting at the neighboring table gingerly raised a cream puff to her nose and sniffed it. An equation with too many unknowns, I said, is no longer an equation, but chaos. That's something for your friend the mathematician, said Marko, and ordered another glass of boza. Why not? I thought, though not just then but several days later, when I found a slip of paper in my mailbox with a yellow star and superimposed on the star, a fat black swastika. That morning in Minut a piece of mine had appeared about the necessity of tolerance if a civil society is to succeed, and I was sure that the clumsy drawing was in response to my suggestion that we should not suspect someone simply because he or she is Chinese, gay, Jewish, or a social outcast, for to doubt them means to have no faith in ourselves, it means having nothing. The mathematician, my former schoolmate, had nothing to do with this, but I hoped he could guide me. We learn sometimes from those we least expect to learn from, or from whom we expect something entirely different. However I didn't feel like chasing him around his high-rise, so I called the woman who had run into him from time to time before she moved to Banovo Brdo, and asked if she could somehow find Dragan Mišović's phone number for me. We all have phones nowadays, I said, he cannot possibly live without one. If he can wear a winter coat in midsummer, she said, he can live without a phone. She promised to call people who went to school with us, and whom she had seen more often before she had moved. She mentioned several names, but none of them rang a bell. Maybe you weren't in the same class, said Marko when I told him about it. He, said Marko, knew the first and last name of every single classmate of his, even the desk and row each of them sat in. I can draw you the layout of my entire classroom, he added, and if he had had a piece of paper and a pencil with him at the time, no doubt he would have done just that. The woman who used to run into Dragan Mišović got in touch with me the next day. She had managed, she boasted, to get his phone number from the first person she'd called, because she, meaning the other person, had organized our most recent class reunion and had everybody's phone numbers. She dictated the number to me, cautioning that Dragan Mišović seldom answered his phone and that I would have to be persistent and call repeatedly until he finally picked up. I called him immediately. My name meant nothing to him, and only when I reminded him of the interpretation of the circle and triangles did he remember who I was. That's not why I am calling, I said. So, said Dragan Mišović, everything's clear? I said nothing. I understand, said Dragan Mišović, sometimes mathematicians get a little carried away, like most professionals, though I should tell you, he said, that I later thought I might write you an addendum, because the next day, that diagram reminded me of the initial step in the iterative process of construction of one of the first known fractals, called the Sierpiński Triangle. Sure, I said. What else could I say? I won't get into the whole story, said Dragan Mišović, but that fractal grew from a random toss of a die, and many theorists of dynamical systems were entranced by it, believing that this procedure demonstrated how order comes from chaos, which served the members of the Brussels School of Ilya Prigogine as proof that the universe didn't have to obey the Second Law of Thermodynamics, or that the system need not ultimately end in chaos and collapse, but instead at a certain moment it would begin to organize itself into another form. Sure, I said again. Of course, Dragan Mišović said, I don't believe that at all, for the simple reason that it's extremely naive, even when expressed in this reduced form. He stopped talking, and for a while we were both silent. I could hear him breathe, just as he could probably hear me breathe, though I tried tucking the receiver under my chin, away from my mouth. Then Dragan Mišović coughed, and said, If that wasn't it, what did you want to ask me? I coughed too and asked, Is the number of unknowns in an equation limited, I mean, what happens with an equation in which there are too many unknowns? Those are two separate questions, said Dragan Mišović. The answer to the first question is simple: no. What about the other question, I asked, the same answer? Depends, said Dragan Mišović, on how you define "too many unknowns." I don't define them at all, I said, that's why I called you. Take, he went on, equations with two unknowns, you probably remember those, they describe many curves in the plane, so the set of pairs (x,y) that satisfies the equation f(x,y) = o makes a curve. For example, x 2 + y2 = I is an equation for a circle with a diameter of 1 and its center at origin. In other words, said Dragan Mišović, that phrase of ours, "too many unknowns," represents a key idea of both Descartes and Fermat, which ties algebra to geometry or the equation to the curve. Your question, he said, contains analytical geometry in all its dimensions, and I would need several hours just to get started. Oh, I said. That's the reason, Dragan Mišović continued, it would be useful to know why you're asking me, because then I could be more precise. Let me put it this way, I said, over the past few days I have come up against a multitude of unknowns, and I am eager to understand just one, because if the unknowns keep multiplying, I said, soon it will no longer be an equation but sheer chaos. Sometimes chaos can be an equation, said Dragan Mišović, but we're better off not going there, let's try to look at it in a different way, or else, he said, let's assume that among those unknowns only one is a genuine unknown, the rest are its parameters. If we do that, he continued, it gets easier. I didn't know why it would get easier, but tacitly I agreed. Of course, that is possible only under certain technical conditions, said Dragan Mišović, which are given by the Implicit Function Theorem. Maybe, I mused, maybe I should never have called him. Don't worry, he said, as if reading my thoughts, I won't trouble you with all the particulars, and besides, I remember how much you loathed math in gymnasium. That's not true, I protested, it's not that I loathed it, it's that I wanted nothing to do with it. You can put it that way if you like, said Dragan Mišović, but memories are a lot like chaos, so it's better for us to leave them be. In this case, he continued, I will only say that this theory tells us that in the corresponding set of equations some of the variables are defined as functions of other variables, on condition, of course, that the Jacobian is nonzero. Sure, I said. So, said Dragan Mišović, if all those conditions are met and we isolate a single unknown in your equation, which we will call the privileged unknown, and we proclaim all others to be its parameters, then we arrive at a new function, we will call it function G, which satisfies the initial equation, even though, and this is the niftiest part of this whole business, we have no idea what that function is or what it looks like. In other words, and I'll conclude with this, said Dragan Mišović, there is a solution that can be expressed as a function, but nothing that tells us how to formulate it more closely. So you know, I said, yet you don't know. No, said Dragan Mišović, you don't know, yet you know. I don't understand a word of this, I confessed. It is pretty simple, he continued patiently, choose one among all the unknowns, and when you solve that one, the others will open. You mean to say, I asked, that they are interconnected after all? It is late for a conversation about paranoia, answered Dragan Mišović, then cleared his throat and hung up. I listened for a while to the white noise coming from the phone cables, then hung up. Did you really expect, Marko asked when we took a stroll the next evening, that he would give you a straight answer? No, I said. The promenade was packed with people, children were shrieking, girls zipped by on roller skates, boys whistled and shouted. Restaurant barges rocked on the water and blasted loud music, from turbo folk to reggae. The days were getting longer, and the sun hung motionless on the western rim of the horizon. I suggested to Marko that we buy ice cream on a stick, but he said he'd rather not, confessing to his fear of getting a splinter in his tongue. That can't happen, I said, but I got us ice cream cones. We perched on the steps going down to the Danube and licked our ice cream in silence. The steps continued into the water, as if descending into Atlantis. The river surface was covered in ripples, and small waves splashed soundlessly against the concrete. Someone at the top of the stairs called out, Look at the sky, it'll rain tomorrow! Everyone is a weatherman these days, Marko said. Two boats passed by slowly, on their way to the marina by the high-rise, and water splashed noisily in the corners of the steps. I think I knew what he wanted to say to me, I said. Marko raised his eyebrows quizzically. First of all, I said, my heart pounding, I must accept the possibility that everything is interconnected, that nothing exists in isolation, that everything is part of a whole, which means that what I don't know and don't understand, the questions and dilemmas I am up against, are also interconnected. Marko persisted in his silence, sticking his tongue as far into his cone as it would go. A white mustache took shape on his upper lip. Another boat passed by, moving along the river toward the high-rise, and again the wavelets gurgled in the corners of the steps. Just tell me, said Marko, how you'll decide what tie there is between the slap on the quay, the sign on the sidewalk, the manuscript on the Kabbalah and history, the anti-Semitic threats, this place that behaves as if it is a hole outside of time, and whatever else, I mean, how will you establish from which of these the others originate, or into which they flow, which is more or less the same thing? I said nothing; I didn't know. Even today I don't know. Jaša Alkalaj, however, didn't hesitate for a second when I asked the same question several days later at his studio. The Kabbalah, he said. Isak Levi sighed, and Jakov Švarc dismissed this comment with a wave of the hand. Ignore them, said Jaša Alkalaj, they are slaves of linear logic, for them it can only be one thing or another, they can never embrace the notion that something may be both one thing and another, at one and the same time. For them the glass is either full or empty, he said, and they don't understand that an empty glass is also full, just as a full glass is also empty. Nonsense, countered Isak Levi, if that were the case, you would be able to answer the question of what happens when I drink half the liquid from a full glass: is the glass then half empty or half full? Both, said Jaša Alkalaj, how many times do I have to tell you? He turned to me: This is how they torment me, he said, like true unbelievers. Who? chimed in Jakov Švarc, us — the unbelievers? You are the only one of us who never goes to temple. My body is my temple, said Jaša Alkalaj, what do I need a synagogue for? That's why the Jews are in trouble, said Jakov Švarc, instead of coming to God, they expect God to come to them. Isak Levi pounded the table, Are we going to argue, which we can always do, or are we going to listen to this man who in coming here is risking his life? If nothing else, he said, we ought to respect that. Sure, sure, said Jaša Alkalaj and Isak Levi, then both looked at me, probably expecting me to say something. Nothing came to mind. I thought it might be good to go out on the balcony and see if anyone shifty was hanging around the building entrance, but I didn't want to unsettle them. They were already worried by the anti-Jewish messages scrawled on my front door; they wanted, like that neighbor of mine, to go straight to the police, and I barely managed to convince them that this was not called for, but I had to promise I'd write about that subject in my column in