At an early age he started writing for the theatre and his comedies are rated with the best produced in Italy in the 16th century. But even before he began his professional writing for the stage, he had developed an interest in magic and anything approaching the magical. This avocation was developed during the rest of his life. Porta was very fond of secrets and secret societies, founding the Academy of Secrets at Naples. He was also a member of the Roman Academy of the Lynxes, scientific society founded in 1603--named for its trademark. Even magic inks for secret writing were an attraction to him. For years it was generally believed that Porta invented the _camera obscura_ but, as we have seen, it was known long before he was born. At the time of the discovery of photography Porta’s title to the invention of the camera was discussed and it was definitely established that while he made some refinements and, of course, devised some special uses, he had nothing to do with its invention. When about 15, Porta began the investigations which led to the writing of _Magia Naturalis, sive de Miraculis Rerum Naturalium_, “Natural Magic, or the wonders of natural things.” The material was published five years later, at Naples, in four “books”, or large chapters. Through the years he increased his notes on the subject and in 1589 the work was printed in twenty chapters. Porta’s _Natural Magic_ was a popular book, a best-seller of the day. It was first translated into English and published in London in 1658. It was also translated into many other languages. _Natural Magic_ contains a wide variety of subjects, including developments in the light and shadow art-science. Porta published the first detailed explanation of the construction and use of the _camera obscura_ in the fourth “book”. “A system by which you can see, in their own colors, in the darkness objects outdoors lighted by the sun,” was Porta’s title for the section. He continued: If anyone wishes to see this effect, all the windows should be closed, and it would be helpful if the cracks were sealed so that no light may enter to ruin the show. Then in one window make a small opening in the form of a cone with the sun at the base and facing the room. Whiten the walls of the room or cover them with white linen or paper. In this way you will see all things outside lighted by the sun, as those walking in the streets, as if their feet were upwards, the right and left of the objects will be reversed and all things will seem interchanged. And the further the screen is from the opening, proportionately the larger the objects will appear; the closer the paper screen or tablet, is drawn to the hole, the smaller the objects will appear.