Alas, the history of opinion is, in one of its most extensive branches, the history of error. The senses are the single source of our ideas, and furnish its models to the imagination. Hence that nearly incorrigible disposition to judge what we are ignorant of by what we know; hence those deceptive analogies to which the primitive rudeness of men surrenders itself. '_As they watched nature, as their eyes wandered to the surface of a profound ocean, instead of the far-off bed hidden under the waters, they saw nothing but their own likeness._ Every object in nature had its god, and this god formed after the pattern of men, had men's attributes and men's vices.'[41] Here, in anthropomorphism, or the transfer of human quality to things not human, and the invention of spiritual existences to be the recipients of this quality, Turgot justly touched the root of most of the wrong thinking that has been as a manacle to science. [Footnote 41: P. 601.] His admiration for those epochs in which new truths were most successfully discovered, and old fallacies most signally routed, did not prevent Turgot from appreciating the ages of criticism and their services to knowledge. He does full justice to Alexandria, not only for its astronomy and geometry, but for that peculiar studiousness 'which exercises itself less on things than on books; whose strength lies less in producing and discovering, than in collecting and comparing and estimating what has been produced and discovered; which does not press forward, but gazes backward along the road that has already been traversed. The studies that require most genius, are not always those which imply most progress in the mass of men. There are minds to which nature has given a memory capable of comparing truths, of suggesting an arrangement that places these truths in the fullest light; but to which, at the same time, she has refused that ardour of genius which insists on inventing and opening out for itself new lines of discovery. Made to unite former discoveries under a single point of view, to surround them with light, and to exhibit them in entire perfection, if they are not luminaries that burn and sparkle of themselves, at least they are like diamonds that reflect with dazzling brilliance a borrowed light.'