At first sight it might seem an idle observation that the first task of intelligence is to represent the environing reality, a reality actually represented in the notion, universally prevalent among men, of a cosmos in space and time, an animated material engine called nature. In trying to conceive nature the mind lisps its first lesson; natural phenomena are the mother tongue of imagination no less than of science and practical life. Men and gods are not conceivable otherwise than as inhabitants of nature. Early experience knows no mystery which is not somehow rooted in transformations of the natural world, and fancy can build no hope which would not be expressible there. But we are grown so accustomed to this ancient apparition that we may be no longer aware how difficult was the task of conjuring it up. We may even have forgotten the possibility that such a vision should never have arisen at all. A brief excursion into that much abused subject, the psychology of perception, may here serve to remind us of the great
