Animals as well as plants were regarded as " simples " and used in medicine, and a knowledge of them was valued from this point of view.
An elderly dame, too, dwells in my neighborhood, invisible to most persons, in whose odorous herb garden I love to stroll sometimes, gathering simples and listening to her fables; for she has a genius of unequalled fertility, and her memory runs back farther than mythology, and she can tell me the original of every fable, and on what fact every one is founded, for the incidents occurred when she was young.
Simples Reflexions sur le decret Lamentabili et sur l'encyclique Pascendi, 12m0, 277 pages, was published from Ceffonds a few days after the commentary.
In 1779 he published an important investigation of the laws of friction (Theorie des machines simples, en ayant regard au frottement de leurs parties et a la roideur des cordages), which was followed twenty years later by a memoir on fluid resistance.
The simple nature of the alkalies Lavoisier considered so doubtful that he did not class them as elements, which he conceived as substances which could not be further decomposed by any known process of analysis - les molecules simples et indivisibles qui composent les corps.