MICHAEL CONSTANTINUS, a learned Christian of the eleventh century, was by birth a Constantinopolitan of consular rank, and flourished under the Emperor Constantine Monomachus, 1020 A.D. His genius and industry raised him far above the level of his contemporaries; and the celebrated historian Anna Comnena speaks of him as one who had been more indebted for his attainments to his own excellent talents than to the instructions of his preceptors; adding, that having made himself master of all the wisdom of the Greeks and the Chaldæans, he was justly esteemed the most learned man of the age. Thus furnished, he became the chief instructor of the Constantinopolitan youth. He was at the same time the companion and preceptor of the emperor, who became so captivated by the studies and amusements in which Pselius engaged him, that, according to Zonaras, he neglected the concerns of the empire. The Byzantine historians complain, that the emperor, deluded by "the Prince of the Philosophers," the title with which Pselius was honoured, lost the world. Towards the close of his life, Pselius, meeting with some disappointment, retired into a monastery, and soon afterwards died; but the time of his death is uncertain. He was not only the most accomplished scholar, he was likewise the most voluminous writer of his age. He published a great variety of works, both prose and poetical, written with a high degree of eloquence and taste. Besides his Synopsis Organii Aristotelici, Svo, 1597, and his mathematical works; there are sixteen other works which have been printed separately. There are likewise numerous writings of this author still inedited. (For an account of those writings, see Fabricius, and Cave.)