Giovanni Domenico Campanella was born in the year 1568 at Stilo in Calabria, one of the most southern townships of all Italy.  In his boyhood he showed a remarkable faculty for acquiring and retaining knowledge, together with no small dialectical ability.  His keen interest in philosophy and his admiration for the great Dominican doctors, Thomas Aquinas and Albertus Magnus, induced him at the age of fifteen to enter the order of S. Dominic, exchanging his secular name for Tommaso.  But the old alliance between philosophy and orthodoxy, drawn up by scholasticism and approved by the mediaeval Church, had been succeeded by mutual hostility; and the youthful thinker found no favour in the cloister of Cosenza, where he now resided.  The new philosophy taught by Telesio placed itself in direct antagonism to the pseudo-Aristotelian tenets of the theologians, and founded its own principles upon the Interrogation of Nature.  Telesio, says Bacon, was the prince of the novi homines, or inaugurators of modern thought.  It was natural that Campanella should be drawn towards this great man.  But the superiors of his convent prevented his forming the acquaintance of Telesio; and though the two men dwelt in the same city of Cosenza, Campanella never knew the teacher he admired so passionately.  Only when the old man died and his body was exposed in the church before burial, did the neophyte of his philosophy approach the bier, and pray beside it, and place poems upon the dead.

From this time forward Campanella became an object of suspicion to his brethren.  They perceived that the fire of the new philosophy burned in his powerful nature with incalculable and explosive force.  He moved restlessly from place to place, learning and discussing, drawing men towards him by the magnetism of a noble personality, and preaching his new gospel with perilous audacity.  His papers were seized at Bologna; and at Rome the Holy Inquisition condemned him to perpetual incarceration on the ground that he derived his science from the devil, that he had written the book ‘De tribus Impostoribus,’ that he was a follower of Democritus, and that his opposition to Aristotle savoured of gross heresy.  At the same time the Spanish Government of Naples accused him of having set on foot a dangerous conspiracy for overthrowing the vice-regal power and establishing a communistic commonwealth in southern Italy.  Though nothing was proved satisfactorily against him, Campanella was held a prisoner under the sentence which the Inquisition had pronounced upon him.  He was, in fact, a man too dangerous, too original in his opinions, and too bold in their enunciation, to be at large.  For twenty-five years he remained in Neapolitan dungeons; three times during that period he was tortured to the verge of dying; and at last he was released, while quite an old man, at the urgent request of the French Court.  Not many years after his liberation Campanella died.  The numerous philosophical