Date: 1637

"I supposed, too, that in the beginning God did not place in this body any rational soul or any other thing to serve as a vegetative or sensitive soul, but rather that he kindled in its heart one of those fires without light which I had already explained, and whose nature I understood to be no di...

— Descartes, René (1596-1650)

Date: 1641

"I am not that structure of limbs which is called a human body. I am not even some thin vapour which permeates the limbs - a wind, fire, air, breath, or whatever I depict in my imagination; for these are things which I have supposed to be nothing."

— Descartes, René (1596-1650)

Date: 1664

"Indeed, one may compare the nerves of the machine I am describing with the pipes in the works of these fountains, its muscles and tendons with the various devices and springs which serve to set them in motion, its animal spirits with the water which drives them, the heart with the source of the ...

— Descartes, René (1596-1650)

Date: 1664

"And finally, when a rational soul is present in this machine it will have its principal seat in the brain, and reside there like the fountain-keeper who must be stationed at the tanks to which the fountain's pipes return if he wants to produce, or prevent, or change their movements in some way."

— Descartes, René (1596-1650)

Date: 1748, 1749

"Hurried with incessant rapidity by the vortex of blood and animal spirits, one undulation makes an impression, which is immediately effaced by another; the soul pursues it, but often in vain: she must wait to bewail the loss of what she did not quickly lay hold of; and thus it is that the imagin...

— Julien Offray de La Mettrie (1709-1751)

Date: 1748, 1749

"Such is the chaos, such the rapid and continual succession of our ideas; they drive one another successively, as one wave impels another; so that it the imagination does not employ a part of its muscles, poised as it were in an equilibrium upon the strings of the brain, so as to sustain itself s...

— Julien Offray de La Mettrie (1709-1751)