to the development of hypotheses at once
more extensive and more exact, and point to new experiments, which in
their turn furnish new problems to solve. 'So necessity perfects the
instrument; so mathematics finds support in physics, to which it lends
its lamp; so all knowledge is bound together; so, notwithstanding the
diversity of their advance, all the sciences lend one another mutual
aid; and so, by force of feeling a way, of multiplying systems, of
exhausting errors, so to speak, the world at length arrives at the
knowledge of a vast number of truths.' It might seem as if a prodigious
confusion, as of tongues, would arise from so enormous an advance along
so many lines. 'The different sciences, originally confined within a few
simple notions common to all, can now, after their advance into more
extensive and difficult ideas, only be surveyed apart. But an advance,
greater still, brings them together again, because that mutual
dependence of all truths is discovered, which, while it links them one
to another, throws light on one by another.'

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 discoverin