A dog lies dozing upon the mat, and hears a step in the porch without. His behaviour at once shows that this enters into the conscious situation. There is, moreover, a marked difference according as the step has the familiar fall of the master’s tread, the well-known shuffle of the irrepressible butcher’s lad, or an unfamiliar sound. These several situations are, without question, nicely distinguished. Let us suppose the situation of the moment is introduced by a strange footfall. It seems to suggest man; but this cannot be any particular man, since he is as yet invisible and is a stranger. Does the dog, then, frame a general idea of man? Does the chamois do so when, bounding across the snow field, he stops suddenly on scenting the distant footprints of a mountaineer? Do you do so when you hear the bleating of an invisible lamb in the meadow behind yonder wall? Here, again, the answers we give to these questions depend partly on the exact meaning of the term “general idea;” partly on our interpretation of what passes through the mind of the being concerned. We have sought, so far, rather to avoid than to answer these questions. We seem to be on safe ground so long as we content ourselves with saying that the orange and black of the cinnabar caterpillar, the strange footfall, or the trail of the mountaineer, enter as effective elements into the immediate conscious situation. But when we pass to the higher phases of mental development we can no longer wholly ignore such questions. When we are dealing with intellectual human beings, there can be no doubt that they at least are capable of framing, with definite intention, and of set purpose, both general and abstract conceptions. And how do they reach these conceptions? By reviewing a number of past situations, analyzing them, intentionally disentangling and isolating for the purposes of their thought certain elements which they contain, and classifying these abstracts under genera and species--that is to say, into broader and narrower groups. The primary and proximate object of this process is to reach a scheme of thought by which the scheme of nature, as given in experience, can be _explained_. And, no doubt, underlying this primary object is the purpose of guiding future behaviour in accordance with the rational scheme which is thus attained. Man is sometimes described as _par excellence_ the being who looks before and after. All his greatest achievements are due to his powers of reflection and foresight.