Descartes: A Biography

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

In Search of a Career (–) 

Della Porta (–)claimed that, at the age of fifteen, he had writ-

tenTwenty Books of Natural Magic, in which the Riches and Delights of the

Natural Sciences are Demonstrated, and that he had enlarged it significantly

forasecond edition thirty-five years later.Areprint of the latter was

published in Hanover in the same year as Descartes’ request to Beeckman

(). Della Porta distinguished two kinds of magic, ‘one infamous, and

unhappy, because it hath to do with foul spirits, and consists of Inchant-

ments and wicked curiosity. The other is Magick Natural...others have

named it the practical part of Natural Philosophy, which produceth

her effects by the mutual and fit application of one natural thing unto

another.’He argued that since magic is the practical part of natural

philosophy, a magician (in this sense) should be ‘an exact and very per-

fect philosopher.’Della Porta’s natural philosophy was still very much

dependent on scholastic principles, such as the claim that all compound

bodies are composed of matter and form.Despite this, Bookprovides

avery competent and informed summary of discoveries in optics, includ-

ing how external events may be represented on the wall of a dark room

through a small aperture in the wall – which, he claims, helps to explain

how vision occurs, and how the philosophical problem of ‘intromission’

is resolved – and how parabolic lenses can be used to transmit letters an

infinite distance, even to the moon.Fordella Porta, then, natural magic

was equivalent to applied physics.

This tolerant and extremely heterogeneous intellectual climate, in-

spired by neoplatonic mysticism and magic, may seem to us in retrospect to

be an unlikely birthplace for modern science. However, it unambiguously

supported the study of the apparently hidden powers of natural phenom-

ena even if it knew little of their precise nature, and it strongly encouraged

the application of mathematical methods to astronomy. Descartes’ lim-

ited exposure to this vast literature is reflected in some of his earliest

writings, which are discussed in thenext chapter.The vague hints of a

general method proposed by Lull and reported in Sanchez’sAdmirable

and General Methodmay also have inspired Descartes with the ideal of

a single method by which all the sciences can be discovered and unified

along the lines explored subsequently in theRules.However, within ten

years of these fumbling inquiries, Descartes’ initial hope of a privileged

access to universal knowledge, discovered by an especially luminescent

‘natural light’, turned to suspicion about anyone who even mentioned

secrets. He wrote to Mersenne,November:‘Assoon asIeven