40 w. H. WINCH: applied to psychological operations where it is not really operative. As the development and function of imagination still form a subject of dispute among psychologists, it may be well to attempt to approach the matter in such a way as may account for the differences. We tend to consider ' sensation ' as dependent wholly upon external objects, and this attitude tends to resolve differences in our perceptive judgments into differences due to factors derived from imagination. If you see what I do not see, you have imagined something which is not there, is too fre- quently our unspoken attitude. But ' sensation ' itself is not the fixed absolute which this form of Eealist philosophy requires. Not only are perceptive judgments likely to be erroneous, well-known daily illu- sions serve sufficiently to demonstrate that, but comparative psychology refuses to allow the fixity of the atomic elements even when uncompounded. Consider, for example, the perception of colour among different peoples at different periods. The colour sense of ancient races, Homer's Greeks to wit, and of existing primi- tive races is extremely defective. Observations on children show how gradually developed colour vision is. But what I am especially concerned to note is the kind of argument which is resorted to by those who take the opposite view. In the Acropolis at Athens we find a blue bull, a blue horse, a man with blue hair (probably 600 B.C.), and it is argued that these decorative instances demonstrate the appreciation of blue, notwithstanding the defect in nomenclature for blue. It is so hard to believe that the sensations of other people from the same object may be different from ours. Yet surely, the difficulty ceases if we suppose that the artist could not distinguish ' blue ' from ' black,' this lack of distinction being now found among primitive people who can neither appreciate the distinction when these colours are presented to them, nor possess the terms of distinction in their language. 1 The bearing of this discussion on the function of imagina- tion in play may seem remote, but I will endeavour to estab- lish the connexion. Just as we are strongly disposed to think that the savage sees what we see, so with the child at play ; we interpret his wild percepts with the aid of the fol- lowing presuppositions : i. That the child receives the same sensations as we do. 1 Report of Cambridge Expedition to Torres Straits, vol. ii.