Descartes.
We must say in general: "This is made by figure and motion for it is true." But to say what these are, and to compose the machine, is ridiculous, for it is useless, uncertain, and painful. And if it were true we do not think that all philosophy is worth one hour of pain.
I cannot forgive Descartes.
If an animal did by mind what it does by instinct, and if it spoke by mind what it speaks by instinct, in hunting, and warning its companions that the quarry is found or lost, it would certainly also speak in regard to those things which affect it more strongly, as for instance, "Gnaw me this cord which hurts me, and which I cannot reach."
The story of the pike and frog of Liancourt. They do it always and never otherwise, nor any other thing of mind.
The calculating machine works results which approach nearer to thought than any thing done by animals, but it does nothing which enables us to say it has any will, as animals have.
When it is said that heat is only the motion of certain molecules, and light the conatus recedendi which we feel, we are surprised. And shall we think that pleasure is but the buoyancy of our spirits? We have conceived so different an idea of it, and these sensations seem so removed from those others which we say are the same as those with which we compare them. The feeling of fire, the warmth which affects us in a manner wholly different from touch, the reception of sound and light, all this seems to us mysterious, and yet it is as material as the blow of a stone. It is true that the minuteness of the spirits which enter into the pores touch different nerves, yet nerves are always touched.
What is more absurd than to say that inanimate bodies have passion, fear, horror, that insensible bodies, without life, and even incapable of life, have passions, which presuppose at least a sensitive soul to feel them, nay more, that the object of their terror is a vacuum? What is there in a vacuum which should make them afraid? What can be more base and more ridiculous? Nor is this all; it is said they have in themselves a principle of motion to avoid a vacuum. Have they arms, legs, muscles, nerves?
How foolish is painting, which draws admiration by the resemblance of things of which we do not admire the originals.
In the same way that we injure the understanding we injure the feelings also.