These were his two great Latin Works, "De Minimo" and "De Immenso," the introduction to the latter being the "De Monade." He worked at these with his own hands. In the introduction to the former his publisher stated that before its final revision Bruno had been hurriedly called away by an unforseen chance. This sudden departure may have been due to a refusal of the town Council to permit his residence there, or it may have been a call to Zürich, where he spent a few months with one Hainzel, who had a leaning toward the Black Arts. Bruno wrote for him "_De Imaginum Compositione_," a manual of his Art of Memory. In this Swiss city he also dictated a work "_Summa Terminorum Metaphysicorum_," which was not published until 1609, and then in Marburg. But Bruno returned to Frankfort in 1591, where he obtained permission to publish his _De Minimo_. This work was on the "three fold minimum and measurement, being the elements of three speculative and several practical sciences." This like the two next mentioned was a Latin poem, after the fashion of Lucretius. The _De Monade, Numero et Figura_ dealt with the Monad, and with the elements of a more esoteric science, while in the _De Immenso et Innumerabilibus_, the Immeasurable and Innumerable, he dealt with the Universe and the worlds. These three poems contain Bruno's complete philosophy of God and Nature. While thus staying in Frankfort for the second time Bruno was invited by a young Venetian patrician to pay him a visit, and become his tutor in those arts in which the philosopher excelled. It was the most unfortunate event in Bruno's unhappy life when he accepted this apparently tempting invitation. Mocenigo, his host, was of good family, but shallow, vain, weak-minded and dishonest, with the fashionable taste of his day for the black arts. It is quite possible that he was moreover the tool of the Inquisition, which had long desired to entrap Bruno. It is probable moreover that the latter quite failed to appreciate how unenviably he was regarded by that Church to which he still felt that he belonged. Furthermore Venice was then a Republic and free, and he longed for his beloved Italy again. En route to Venice he spent three months in Padua, teaching there and gathering around himself pupils, even in that short time. He had barely left it when Galileo was invited there to teach; as Riehl has said, "the creator of modern science following in the steps of its prophet."