Mem. To correct my language & make it as philosophically nice as possible—to avoid giving handle. If men could without straining alter the convexity of their crystallines, they might magnify or diminish the apparent diameters of objects, the same optic angle remaining. The bigness in one sense of the pictures in the fund is not determin’d; for the nearer a man views them, the images of them (as well as other objects) will take up the greater room in the fund of his eye. Mem. Introduction to contain the design of the whole, the nature and manner of demonstrating, &c. Two sorts of bigness accurately to be distinguished, they being perfectly and _toto cælo_ different—the one the proportion that any one appearance has to the sum of appearances perceived at the same time wth it, wch is proportional to angles, or, if a surface, to segments of sphærical surfaces;—the other is tangible bigness. Qu. wt would happen if the sphæræ of the retina were enlarged or diminish’d? We think by the meer act of vision we perceive distance from us, yet we do not; also that we perceive solids, yet we do not; also the inequality of things seen under the same angle, yet we do not. Why may I not add, We think we see extension by meer vision? Yet we do not. Extension seems to be perceived by the eye, as thought by the ear. As long as the same angle determines the _minimum visibile_ to two persons, no different conformation of the eye can make a different appearance of magnitude in the same thing. But, it being possible to try the angle, we may certainly know whether the same thing appears differently big to two persons on account of their eyes. If a man could see ... objects would appear larger to him than to another; hence there is another sort of purely visible magnitude beside the proportion any appearance bears to the visual sphere, viz. its proportion to the M. V. Were there but one and the same language in the world, and did children speak it naturally as soon as born, and were it not in the power of men to conceal their thoughts or deceive others, but that there were an inseparable connexion between words & thoughts, so yt _posito uno, ponitur alterum_ by the laws of nature; Qu. would not men think they heard thoughts as much as that they see extension(229)? ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ All our ideas are adæquate: our knowledge of the laws of nature is not perfect & adæquate(230). ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ (M388) Men are in the right in judging their simple ideas to be in the things themselves. Certainly heat & colour is as much without the mind as figure, motion, time, &c. ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐