The Renaissance scientist and dramatist Giambattista della Porta (1535-1615) is noted for his biological index of personality tendencies. He wrote 17 plays.
In the course of his writings Giambattista della Porta made misstatements about his age, presumably because he enjoyed posing as a man of mystery or perhaps because, in making himself younger than he was, he would become known as a child prodigy. In spite of his own misrepresentation, the year of his birth has been reliably established as 1535. He came from minor Neapolitan nobility.
In the spirit of the Renaissance his father's house was a kind of academy where young della Porta and his two brothers were introduced to the arts and sciences. Giambattista was tutored by an uncle. Along with the humanism of the Renaissance, his program of studies emphasized the sciences, pure and applied. In his youth he got his first taste of drama, and it is probable that some of his plays are later revisions of what he had written as a young man. From his older brother he learned astrology, and from his younger one he obtained a collection of crystals and of geological specimens.
Sometime in the 1550s, della Porta founded the Academy of the Segreti. In this group, interest was divided between genuine scientific observations and what is now recognized as magic. The Magiae naturalis (1558; 2d ed. 1559), destined to be one of his two most famous works in natural science, probably grew out of this first academy. It relates experiments on herbs, chemicals, and magnetism and includes opinions on the occult.
About 1580, della Porta was denounced before the Inquisition for works in magic and prophecy and was commanded to give up his practice of illicit arts. About this time also, he was befriended by the influential Cardinal Luigi d'Este, who invited him to Rome and later to Venice. During the Venetian period he worked on the parabolic mirror and on an occhiale, probably a magnifying glass. His work on lenses led to the false claim, which he encouraged, that he invented the telescope.
In della Porta's most renowned scientific work, De humana physiognomia (1586), he maintained that the physical characteristics of human beings are clues to their personalities. By viewing such physical traits as tendencies rather than as determining factors, della Porta was able to avoid fatalism and affirm individual responsibility.
In 1603 della Porta joined in an effort to keep alive a society that was later to bloom as the Academy of the Lincei and that was to claim Galileo as a member. Meanwhile, della Porta wrote works on science and mathematics and authored 17 plays, most of them comedies, which proved him to be a true Renaissance type, a humanist as well as a scientist.
Louise George Clubb, Giambattista della Porta: Dramatist (1965), deals with the literary work. For Della Porta's scientific work see George Sarton, Six Wings: Men of Science in the Renaissance (1957), and Lynn Thorndike, A History of Magic and Experimental Science, vols. 7 and 8 (1958).