Descartes, René (1596-1650)

Treatise on Man

Paris

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 can inflate the sails of a ship and tighten all the ropes to which the sails are attached)."

Now, the substance of the brain being soft and pliant, its cavities would be very narrow and almost all closed (as they appear in the brain of a corpse) if no spirits entered them. 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 can inflate the sails of a ship and tighten all the ropes to which the sails are attached). It follows that at such times the machine is disposed to respond to all the actions of the spirits, and hence it represents the body of a man who is awake. Or at least the spirits have enough force to push against some parts of the surrounding matter in this way, and so make it tight, while the other parts remain free and relaxed (as happens in parts of a sail when the wind is a little too weak to fill it). At such times the machine represents the body of a man who is asleep and who has various dreams as he sleeps.

Vehicles::Ship::Sail Weather::Wind

Reading

Descartes, René. The Philosophical Writings of Descartes. Trans. John Cottingham, Robert Stoothof, and Dugald Murdoch. Cambridge: Cambridge University Press, 1985.

01/30/2012