Descartes: A Biography

c CUNYB/Clarke     December, :

Magic, Mathematics, and Mechanics 

with other figures which squirt out water as they turn.’Each solution

is illustrated on a facing page with a detailed diagram of the proposed

construction.

The implications of these models were evident in Descartes’ approach

to modeling animals as machines in the earlys. Hewrote in theTreatise

on Man:

The nerves of the machine that I am describing can be compared to the pipes in the

mechanical parts of these fountains, its muscles and tendons to various other engines

and springs which serve to operate these mechanical parts, its animal spirits to the

water that drives them, the heart to the source of the water, and the brain’s cavities to

the apertures. Moreover, respiration and similar actions which are normal and natural

to this machine, and which depend on the flow of spirits, are like the movements of a

clock or mill, which the normal flow of water can make continuous. External objects,

which by their mere presence act on the organs of sense and thereby cause them to

move in many different ways...are like strangers who on entering the grottoes of

these fountains unwittingly cause the movements that take place before their eyes. For

they cannot enter without stepping on certain tiles which are arranged in such a way

that, for example, if they approach a Diana bathing they will cause her to hide in the

reeds, and if they move forward to pursue her they will cause a Neptune to advance

and threaten them with his trident. (x.–)

De Caus’s book on machines, including hydraulic machines that could

simulate the movements and sounds of animals and human beings, pro-

vided a model of explanation that contrasted starkly with anything that

Descartes might have borrowed from the Rose Cross fraternity. The con-

trast between mechanical and magical powers – and the corresponding

contrast between explanations that use mechanical models and ‘under-

standing’ that presupposes mystical enlightenment – reflected the twin

interests of the Holy Roman emperor, Rudolph II, and of the circle of

dedicated researchers that gathered around the court at Prague. These

two cultures were as incompatible as their subsequent history confirmed.

Descartes had not reached a point, in,atwhich he was sufficiently

clear about the choice to be made, although the options available became

very clear in the earlys.The transition was made after he returned

to the United Provinces in.

At the conclusion of this rather unstructured period of his life, Descartes

was thirty-two years old. He had written little apart from an incomplete

autobiographical sketch, and an incomplete draft of a general method that

he was forced to abandon. He had lost much of his original enthusiasm

formathematics, and had begun to work in optics with the assistance of