Zoology

Mechanistic Basis of Physiology

René DESCARTES. A fragment from De homine figuris et latinitate donatis a Florentio Schuyl, etc., Leyden, 1662; tr. of this fragment by J. P. Mahaffy in his Descartes, Philadelphia, 1881.

I desire you next to consider that all the functions which I have attributed to this (animal) machine, such as digestion, the heating of the heart and arteries, nutrition and growth, breathing, waking and sleep, the perception of colours, sounds, tastes, heat, and other such qualities by the external senses, the impression of their ideas in the organ of sensus communis and of imagination, the retention or impression of these ideas in memory, the internal motions of appetites and passions; and finally, the external movements of all the limbs, which follow so suitably as well from the action of objects presented to sense as from the passions and impressions which are found in the memory, that they imitate as perfectly as is possible those of a real man,—I desire you to notice that these functions follow quite naturally in the machine from the arrangement of its organs exactly as those of a clock, or other automaton, from that of its weights and wheels; so that we must not conceive or explain them by any other vegetative or sensitive soul, or principle of motion and life, than its blood and its spirits agitated by the heat of the fire which burns continually in its heart, and which is of no other kind than all the fires which are contained in inanimate bodies.