Avicenna, or Ibn Sina, the tenth-century Persian scientist-philosopher, is beyond doubt the most provocative figure in the history of thought. With a wideness of range, a vigour of thought, and a unity of conception unequalled among the philosophers, his thoughts extended far beyond the Eastern lands, giving rise to the most complete philosophical system that the Islamic world was to have. Avicenna’s works can be of guidance to those in the East who are meeting the challenge of Western civilization; and to those in the West who have yet to find a basis on which to harmonize scientific with spiritual values. This book attempts to present them to the general reader.