FIRST THOUGHTS ON THE GENERATION OF ANIMALS
INTRODUCTION
This short extract illustrates how Descartes thought that only an infinitesimal force was required to make the difference between a muscle moving in one direction or completely the opposite direction.
No-one knows when this document was written, and it might even be a compilation of drafts from different periods in Descartes’ life. It was first published in a collection of posthumous works: Opuscula Posthuma (Amsterdam, 1701). Some earlier scholars doubted whether it was written by Descartes himself, but in the 19th century Foucher de Careil proved that at least some of it had been copied out by Leibniz from the authentic collection of Descartes’ unpublished writings.
I have translated from Descartes’ Latin in Adam and Tannery, Volume XI. Page numbers in square brackets refer to this edition.