Language was not only a means of communication for new ideas, it was also a repository for the history of progress. In an article on Languages which Turgot had projected for the Enclyclopédie but which, like so many of his plans, never came to fruition, he intended to show that throughout the ages language was an index of the stadial development of nations, since words were invented only when there were ideas demanding utterance. The mere existence of certain words was witness to a complex civilization.
[…Turgot:] “The study of language, if well done, would perhaps be the best of logics. In analyzing, in comparing words of which they are fashioned, in tracing from the beginning the different meanings which they acquired, in following the thread of ideas, we will see through which stages, through which metamorphoses men passed….This kind of experimental metaphysics would be one and the same time the history of the human mind and the history of the progress of its thoughts, always fitted to the needs which gave birth to them. Languages are at once their expression and their measure.”
[…]Like Vico, Turgot’s fragments also recognized a stage of human consciousness which was so primitive that man could only give voice to his ideas in myth, in metaphor, in pictorial images. And for Turgot, as for Hume, there is a manifest superiority in the abstract attitude over the concrete. Turgot was ultimately led by his worship of reason to prefer purest mathematical abstraction over all forms of knowledge and to look upon the metaphors and images in which the ancients communicated their ideas as a sort of baby-talk, expressive perhaps, but a form which had to be outgrown. Eighteenth-century French thinkers like Turgot were conscious of the death of the poetic spirit in their society, and they did not regret it.
—Frank E. Manuel, “Turgot, Barone De L’Aulne,” The Prophets of Paris (Harvard U. Press, 1962, pp30-32)