Much was devoted to the proof of the Copernican discovery.

Orthodox theology was indirectly combated or plausibly caressed.

There are consequently many pages in his dialogues which do not interest a modern reader, seeing that we have outlived the conditions of thought that rendered them important.

In the process of his argument, he established the theory of a philosophical belief, a religion of religions, or 'religione della mente,' as he phrased it, prior to and comprehensive of all historical creeds.

He speculated, as probabilities, the transmigration of souls, and the interchangeability of types in living creatures.