"There are other ways to identify the elements ... vibration resonances, quantum wavelengths ... somebody named Lewis came out a couple years ago with a Quantum Periodic Table...." "They're covering all the possibilities. There are messages for many different levels of understanding. We just decoded the simplest one." "Yeah." I noticed that as he spoke, Rizzo's hand--still tightly clutching the pencil--was trembling and white with tension. "Well?" Rizzo licked his lips. "Let's get to work." * * * * * We were like two men possessed. Eating, sleeping, even talking was ignored completely as we waded through the hundreds of sheets of paper. We could decode only a small percentage of them, but they still represented many hours of communication. The sheets that we couldn't decode, we suspected, were repetitions of the same message that we were working on. We lost all concept of time. We must have slept, more than once, but I simply don't remember. All I can recall is thousands of numbers, row upon row, sheet after sheet of numbers ... and my pencil scratching symbols of the various chemical elements over them until my hand was so cramped I could no longer open the fingers. The message consisted of a long series of formulas; that much was certain. But, without punctuation, with no knowledge of the symbols that denote even such simple things as "plus" or "equals" or "yields," it took us more weeks of hard work to unravel the sense of each equation. And even then, there was more to the message than met the eye: "Just what the hell are they driving at?" Rizzo wondered aloud. His face had changed: it was thinner, hollow-eyed, weary, covered with a scraggly beard. "Then you think there's a meaning behind all these equations, too?" He nodded. "It's a message, not just a contact. They're going to an awful lot of trouble to beam out this message, and they're repeating it every seven hours. They haven't added anything new in the weeks we've been watching." "I wonder how many years or centuries they've been sending out this message, waiting for someone to pick it up, looking for someone to answer them." "Maybe we should call Washington...." "No!" Rizzo grinned. "Afraid of breaking radio silence?" "Hell no. I just want to wait until we're relieved, so we can make this announcement in person. I'm not going to let some old wheezer in Washington get credit for this.... Besides, I want to know just what they're trying to tell us." It was agonizing, painstaking work. Most of the formulas meant nothing to either one of us. We had to ransack the dome's meager library of microspools to piece them together. They started simply enough--basic chemical combinations: carbon and two oxygens yield CO_{2}; two hydrogens and oxygen give water. A primer ... not of words, but of equations.