in an emphatical manner, when the child’s eye is directed to the nurse with earnestness and desire. The association therefore of the sound nurse, with the picture of the nurse upon the retina, will be far stronger than that with any other visible impression, and thus overpower all the other accidental associations, which will also themselves contribute to the same end by opposing one another. And when the child has gained so much voluntary power over his motions, as to direct his head and eyes towards the nurse upon hearing her name, this process will go on with an accelerated velocity. And thus, at last, the word will excite the visible idea readily and certainly.
The same association of the picture of the nurse in the eye with the sound nurse, will, by degrees, overpower all the accidental associations of this picture with other words, and be so firmly cemented at last, that the picture will excite the audible idea of the word. But this is not to our present purpose. I mention it here as taking place at the same time with the foregoing process, and contributing to illustrate and confirm it. Both together afford a complete instance for the tenth and eleventh propositions, i.e. they shew, that when the impressions A and B are sufficiently associated, A impressed alone will excite b, B impressed alone will excite a.
Secondly, This association of words with visible appearances, being made under many particular circumstances, must affect the visible ideas with a like particularity. Thus the nurse’s dress, and the situation of the fire in the child’s nursery, make part of the child’s ideas of his nurse and fire. But then as the nurse often changes her dress, and the child often sees a fire in a different place, and surrounded by different visible objects, these opposite associations must be less strong than the part which is common to them all; and consequently we may suppose, that while his idea of that part which is common, and which we may call essential, continues the same, that of the particularities, circumstances, and adjuncts, varies. For he cannot have any idea, but with some particularities in the non-essentials.
Thirdly, When the visible objects impress other vivid sensations besides those of sight, such as grateful or ungrateful tastes, smells, warmth, or coldness, with sufficient frequency, it follows from the foregoing theory that these sensations must leave traces, or ideas, which will be associated with the names of the objects, so as to depend upon them. Thus an idea, or nascent perception, of the sweetness of the nurse’s milk will rise up in that part of the child’s brain which corresponds to the nerves of taste, upon his hearing her name. And hence the whole idea belonging to the word nurse now begins to be complex, as consisting of a visible idea, and an idea of taste. And these two ideas will be associated together, not only because the word raises them both, but also because the original sensations are. The strongest may therefore assist in raising the weakest. Now, in common cases,
