He gained the patronage of the bishop of Cyprus, who brought him to Venice, where his abilities were immediately recognized by his appointment to the chair of philosophy at Ferrara. He was subsequently invited to Rome by Clement VIII. In spite of his almost incessant controversies with the Aristotelians, he found time to make a comprehensive study of contemporary science. He published in 15 books a treatise on the New Geometry (1587), and works on history, rhetoric and the art of war. He studied ancient theories of music, and is said to have invented the thirteen-syllable verse known subsequently as versi martelliani. In his philosophy he was mainly concerned to defend Plato against the followers of Aristotle.
His two great works, Discussionum peripateticorum libri XV (Basel, 1571), and Nova de universis philosophia (Basel, 1591), developed the view that, whereas Aristotle's teaching was in direct opposition to Christianity, Plato, on the contrary, foreshadowed the Christian revelation and prepared the way for its acceptance. In the earlier treatise he attacks the life and character of Aristotle, impugns the authenticity of almost all his works, and attempts to refute his doctrines from a theological standpoint. In the second and greater work he goes back to the theories and methods of the Ionians and the pre-Socratics generally.
His theory of the universe is that, from God there emanated Light which extends throughout space and is the explanation of all development. This Light is not corporeal and yet is the fundamental reality of things. From Light came Heat and Fluidity; these three together with Space make, up the elements out of which all things are constructed. This cosmic theory is a curious combination of materialistic and abstract ideas; the influence of his master Telesio, generally predominant, is not strong enough to overcome his inherent disbelief in the adequacy of purely scientific explanation.