The city was not generally favourable to heretics, and in 1616 Lucilio Vanini was burnt there for his opinions. A cancelled phrase in the evidence suggests that Bruno's departure from Toulouse was owing to disputes and difficulties regarding his doctrine, but his alleged reason was the civil war that was then raging in the south of France, with Henry of Navarre in the field. While at Toulouse, Bruno seems to have completed a work in more than one volume, the _Clavis Magna_, or "Great Key," a general, and as Bruno thought, a final textbook on the art of memory:--"All the ideas of the older writers on this subject (so far as we are able to make out from the books that have come to our hands), their doctrines and methods, have their fitting place in our invention, which is a superlatively pregnant one, and has appropriated to it the book of the Great Key."[32] One volume only, it appears, was published by Bruno, and that in England, the _Sigillus Sigillorum_. [Sidenote: Works published in Paris.] [Sidenote: _De Umbris._] [Sidenote: _Ars Memoriæ._] [Sidenote: _Cantus Circæus_.] To Paris Bruno came about the close of 1581, and almost at once sprang into fame. A course of thirty lectures on "The thirty divine attributes" (as given by Thomas Aquinas) brought him the offer of an ordinary professorship, but this he could not take, being unable to attend mass. However, his fame reached the ears of the king, Henry the Third, who summoned him to his presence, to know among other things "whether the memory Bruno had, and the art of memory he professed, were natural or due to magic." Bruno proved to him that a powerful memory was a natural product, and dedicated to him a book on the Art of Memory. Henry III. was the son of an Italian mother, and had a keen, if uncritical and dilettante, love of learning. At the time Bruno arrived in Paris philosophy was one of the king's chief hobbies, and the fact had a great influence on Bruno's future. During his stay in Paris Bruno published several works, of which the first perhaps was the "Shadows of Ideas" (_De Umbris Idearum_), 1582, dedicated to Henry III., along with which, but without a separate frontispiece, was the _Art of Memory_ (_Ars Memoriæ Jordani Bruni_); there followed "The Incantation of Circe" (_Cantus Circæus_), 1582, dedicated to Prince Henry of Angoulême, and edited by Regnault. The _De Umbris_ gives the metaphysical basis of the art of memory, the _Ars Memoriæ_ a psychological analysis of the faculty, and an account of the theory of the art itself, while the _Cantus Circæus_ offers first a practical application, and secondly a more elementary account of the theory and practice of the system. Obscurity was, in those days of pedantry, one of the safest ways of securing a hearing: there is nothing of value in Bruno's art except the philosophy by which he sought to support it--a renovated Neoplatonism. It has been pointed out, however, "that the art