Five per cent vision is better than no vision at all. Five per cent hearing is better than no hearing at all. Five per cent flight efficiency is better than no flight at all. It is thoroughly believable that every organ or apparatus that we actually see is the product of a smooth trajectory through animal space, a trajectory in which every intermediate stage assisted survival and reproduction.
[Rebutting the Creationist assertion that fully developed organs could not have arisen 'by chance.']

The human senses (above all, that of hearing) do not possess one set of constant parameters, to be measured independently, one at a time. It is even questionable whether the various 'senses' are to be regarded as separate, independent detectors. The human organism is one integrated whole, stimulated into response by physical signals; it is not to be thought of as a box, carrying various independent pairs of terminals labeled 'ears', 'eyes', 'nose', et cetera.

Through seven figures come sensations for a man; there is hearing for sounds, sight for the visible, nostril for smell, tongue for pleasant or unpleasant tastes, mouth for speech, body for touch, passages outwards and inwards for hot or cold breath. Through these come knowledge or lack of it.