Analogies between intelligence and physical strength are easy to make and often useful. I have used them before and I expect to use them again. But the correspondence is not exact. If to say “genius” is to mean anything, it must do more than name qualities of intelligence that are superior to ignorance in the same way that athleticism is superior to clumsiness. There are such qualities, such matters of degree; but they are not genius.

To use the word genius significantly, I would posit that strength is stable, but intelligence is metastable. These are terms from physics; they have statistical analogs but the terms from physics are more easily illustrated.

Imagine a marble rattling inside a bowl with tall sides. Rest the bowl on flat ground; shake it. Sometimes the marble climbs one side; sometimes another; but always it come to rest on the bottom – and when it falls out, it falls no lower than the bottom. In this bowl the marble’s condition is stable. (Chart the marble’s movements, and you have a bell curve.)

But intelligence is metastable. Imagine the same bowl; but this time, instead of resting it on the ground, put it at the summit of a hill. Mostly the marbles rattle inside this bowl as they did in the other; but sometimes a marble overtops the side, and shoots off down the hill on a trajectory we rattling marbles cannot imagine.

I believe in genius – not in geniuses. All of us spend most of our time rattling around in the bowl. But when the right person thinks about the right subject at the right time, a mind can take a trajectory that briefly places it, not just above all others, but above the sum of all others. In a work of genius, however briefly, a brainpower is concentrated that exceeds the combined brainpower of the rest of the human race. (Or, if not the sum, at least the sum of what language could coordinate to be applied along those lines.) Not a bit-for-bit balance of computations – only an unpredictable and incomparable excession.

A work of genius is recognizable because it arrives, even when it is simple in itself, as a characteristic expression of an unknown order of things – the way that the first artifact discovered from a lost civilization stands, the way the first signal from an alien civilization might stand – standing apart from all you know, not because it is overtly different, but because it implies in its negative space, in its outlines and hollows, a system of beliefs and concerns altogether contained in itself, a strangeness that is not a shock but a rich and intricate surprise.

Maybe this is why I feel such desparate pity for lost books. Sometimes when a book is lost, all that is lost is one more thing in the world; but sometimes when a book is lost, something like a world, something like cities and peoples, falls silent.