...of perception

Passing again beneath the ginkgo, I said to Mr. Okeda that in the contemplation of the shower of leaves the fundamental thing was not so much the perception of each of the leaves as of the distance between one leaf and another, the empty air that separated them. What I seemed to have understood was this: an absence of sensations over a broad part of the perceptive field is the condition necessary for our sensitivity to concentrate locally and temporally, just as in music a basic silence is necessary so that the notes will stand out against it.

[If On A Winter's Night A Traveller, Calvino, I.]