Date: 1664

"The parts of the blood which penetrate as far as the brain serve not only to nourish and sustain its substance, but also and primarily to produce in it a certain very fine wind, or rather a very lively and pure flame, which is called the animal spirits."

— 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: 1664

"Now I maintain that when God unites a rational soul to this machine (in a way that I intend to explain later) he will place its principal seat in the brain, and will make its nature such that the soul will have different sensations corresponding to the different ways in which the entrances to th...

— Descartes, René (1596-1650)

Date: 1664

"You can think of our machine's heart and arteries, which push the animal spirits into the cavities of its brain, as being like the bellows of an organ, which push air into the wind-chests; and you can think of external objects, which stimulate certain nerves and cause spirits contained in the ca...

— Descartes, René (1596-1650)

Date: 1664

"But the source which produces these spirits is usually so abundant that they enter these cavities in sufficient quantity to have the force to push out against the surrounding matter and make it expand, thus tightening all the tiny nerve-fibres which come from it (in the way that a moderate wind ...

— Descartes, René (1596-1650)

Date: 1664

"Now among these figures, it is not those imprinted on the external sense organs, or on the internal surface of the brain, which should be taken to be ideas--but only those which are traced in the spirits on the surface of the gland (where the seat of the imagination and the 'common' sense is loc...

— Descartes, René (1596-1650)

Date: 1664

"That is to say, it is only the latter figures which should be taken to be the forms or images which the rational soul united to this machine will consider directly when it imagines some object or perceives it by the senses."

— Descartes, René (1596-1650)

Date: 1664

"But I shall content myself with telling you more about how the traces are imprinted on the internal part of the brain which is the seat of the memory."

— Descartes, René (1596-1650)

Date: 1664

"Thus they also trace figures in these gaps, which correspond to those of the objects. At first they do this less easily and perfectly than they do on gland H, but gradually they do it better and better, as their action becomes stronger and lasts longer, or is repeated more often. That is why the...

— Descartes, René (1596-1650)