Similarly, M. Perez remarks, “the necessity which children are under of seeing in a detached and scrappy manner in order to see well, makes them continually practise that kind of abstraction by which we separate qualities from objects. From those objects which the child has already distinguished as individual, there come to him at different moments particularly vivid impressions.... Dominant sensations of this kind, by their energy or frequency, tend to efface the idea of the objects from which they proceed, _to separate or abstract themselves_.... The flame of a candle is not always equally bright or flickering; tactile, sapid, olfactory, and auditive impressions do not always strike the child’s sensorium with the same intensity, nor during the same length of time. This is why the recollections of individual forms, although strongly graven on their intelligence, lose by degrees their first precision, so that the idea of a tree, for instance, furnished by direct and perfectly distinct memories, comes back to the mind in a vague and indistinct form, which might be taken for a general idea.”[27] Again, in the opinion of John Stuart Mill, “It is the doctrine of one of the most fertile thinkers of modern times, Auguste Comte, that besides the logic of signs, there is a logic of images, and a logic of feelings. In many of the familiar processes of thought, and especially in uncultured minds, a visual image serves instead of a word. Our visual sensations, perhaps only because they are almost always present along with the impressions of our other senses, have a facility of becoming associated with them. Hence, the characteristic visual appearance of an object easily gathers round it, by association, the ideas of all other peculiarities which have, in frequent experience, co-existed with that appearance; and, summoning up these with a strength and certainty far surpassing that of merely casual associations which it may also raise, it concentrates the attention on them. This is an image serving for a sign—the logic of images. The same function may be fulfilled by a feeling. Any strong and highly interesting feeling, connected with one attribute of a group, spontaneously classifies all objects according as they possess, or do not possess, that attribute. We may be tolerably certain that the things capable of satisfying hunger form a perfectly distinct class in the mind of any of the more intelligent animals; quite as much as if they were able to use or understand the word food. We here see in a strong light the important truth that hardly anything universal can be affirmed in psychology except the laws of association.”[28]