of little circumstances, and a variety of associated ones, which intermix themselves here. Hence the same picture may appear much more like to one person than to another, viz. according as it resembles his idea more or less.
Thirteenthly, Painters, statuaries, anatomists, architects, &c. see at once what is intended by a picture, draught, &c. from the perfection of their visible ideas; and carry off the scene, plan, &c. in their memories, with quickness and facility. All which is still owing to association. But it would be endless to enumerate the instances of associations which this sense affords.
Fourteenthly, It is probable, that fables, parables, similes, allegory, &c. please, strike, and instruct, chiefly on account of the visible imagery which they raise up in the fancy. They are also much more easily remembered on the same account. We may add, that idolatry, heathenish and popish, has made a much quicker and more extensive progress in the world on account of the stability and vividness of visible impressions and ideas, and the difficulty, obscurity, and changeable nature, of abstract notions. And image worship seems even to have been derived in great measure from this source.
Fifteenthly, It would be a matter of great curiosity and use (as far as these speculations can be of any use) to inquire carefully into the progress of the mind, and particularly the fancy, in persons born blind, and compare the result with what is advanced under this proposition, and with other parts of these papers, in order to correct and improve the theory of association thereby. It is probable, that they are considerable losers, upon the whole, in respect of knowledge; though their greater degree of attention, and the superior acuteness of the senses of feeling and hearing, and, consequently, perfection of the ideas of these senses, must give them some particular advantages.
These motions are of two kinds, external and internal. The external are the motions of the globe of the eye, those of the eyelids, and the contractions of the lacrymal, and other neighbouring glands, whereby they are evacuated. The internal are the contractions of the greater and lesser muscular rings of the iris, of the radiated fibres of the iris, and of the ciliar ligaments. I will speak of each of these in order.
I begin with the motions of the globe of the eye. And here I observe, first, that the white tendinous expansions of the four straight muscles reach as far as the cornea; and consequently, that they are thereby exposed in a particular manner to the action of light, when the eye is open, being covered with nothing but a thin membrane. However, the tendinous expansions of the adducens and abducens are much more exposed than those of the
