Avicenna, or Ibn Sina, the tenth-century Persian scientist-philosopher, is beyond doubt the most provocative figure in the history of though. With a wideness of range, a vigour of thought, and a unity if conception unequalled among the philosphists, his thoughts extended far beyond the Eastern lands, giving rise to the most complete philosophical system owed much to his predecessors. Avicenna combined philosphy and medicine with such marked distinction, building an intellectual edifice that could not be surpasses for centuries after him.