Each and every loss becomes an instance of ultimate tragedy–something that once was, but shall never be known to us. The hump of the giant deer–as a nonfossilizable item of soft anatomy–should have fallen into the maw of erased history. But our ancestors provided a wondrous rescue, and we should rejoice mightily. Every new item can instruct us; every unexpected object possesses beauty for its own sake; every rescue from history’s great shredding machine is–and I don’t know how else to say this–a holy act of salvation for a bit of totality.

Lord Kelvin, unable to meet his classes one day, posted the following notice on the door of his lecture room, “Professor Thomson will not meet his classes today.” The disappointed class decided to play a joke on the professor. Erasing the “c” they left the legend to read, “Professor Thomson will not meet his lasses today.” When the class assembled the next day in anticipation of the effect of their joke, they were astonished and chagrined to find that the professor had outwitted them. The legend of yesterday was now found to read, “Professor Thomson will not meet his asses today.”

Neither fire nor wind, birth nor death can erase our good deeds.

Philosophers and psychiatrists should explain why it is that we mathematicians are in the habit of systematically erasing our footsteps. Scientists have always looked askance at this strange habit of mathematicians, which has changed little from Pythagoras to our day.

Some paintings become famous because, being durable, they are viewed by successive generations, in each of which are likely to be found a few appreciative eyes. I know a painting so evanescent that it is seldom viewed at all, except by some wandering deer. It is a river who wields the brush, and it is the same river who, before I can bring my friends to view his work, erases it forever from human view. After that it exists only in my mind's eye. Like other artists, my river is temperamental; there is no predicting when the mood to paint will come upon him, or how long it will last. But in midsummer, when the great white fleets cruise the sky for day after flawless day, it is worth strolling down to the sandbars just to see whether he has been at work.

The advantage is that mathematics is a field in which one’s blunders tend to show very clearly and can be corrected or erased with a stroke of the pencil. It is a field which has often been compared with chess, but differs from the latter in that it is only one’s best moments that count and not one’s worst. A single inattention may lose a chess game, whereas a single successful approach to a problem, among many which have been relegated to the wastebasket, will make a mathematician’s reputation.

What matters in science is the body of findings and generalizations available today: a time-defined cross-section of the process of scientific discovery. I see the advance of science as self-erasing in the sense that only those elements survive that have become part of the active body of knowledge.