TELESIO, BERNARDINO (1509-1588), Italian philoso pher and natural scientist, was born of noble parentage at Cosenza near Naples in 1509. He was educated at Milan, Rome and Padua. He began his attack upon the mediaeval Aristotelianism which then flourished in Padua and Bologna. He began to lecture at Naples and finally founded the academy of Cosenza. In 1565 ap peared his great work De natura rerum iuxta propria principia, which was followed by a large number of scientific and philosophi cal works of subsidiary importance. After his death, at Cosenza in 1588, his books were placed on the Index.
Telesio was the head of the great South Italian movement which protested against the accepted authority of abstract reason, and sowed the seeds from which sprang the scientific methods of Campanella and Bruno, of Bacon and Descartes. He proposed an inquiry into the data given by the senses, from which he held that all true knowledge comes. Instead of postulating matter and form, he bases existence on matter and force. This force has two opposing elements : heat, which expands, and cold, which con tracts. These two processes account for all the diverse forms and types of existence, while the mass on which the force operates re mains the same. The harmony of the whole consists in this, that
each separate thing develops in and for itself in accordance with its own nature while at the same time its motion benefits the rest. The obvious defects of this theory, (1) that the senses alone can not apprehend matter itself, (2) that it is not clear how the mul tiplicity of phenomena could result from these two forces, and (3) that he adduced no evidence to substantiate the existence of these two forces, were pointed out at the time by his pupil, Patrizzi. His system is a forerunner of all subsequent empiricism, and marks the period of transition from authority and reason to ex periment and individual responsibility. Beside the De Rerum Natura, he wrote De Somno, De his quae in were flout, De Mari, De Cometis et Circulo Lacteo, De usu respirationis, etc.
See G. Gentile, Bernardino Telesio, con appendice bibliographico (Bari, 191I) ; E. Troilo, Bernardino Telesio (Modena, i91I).