He believed that the earth is spherical; that the earth and the sea constitute a wonderful globe; that the motions of the heavenly bodies are circular and uniform, or compounded of circular and uniform motions; that the earth revolves on its own axis, and also performs a journey along its own orbit round the sun; that the sphere of the fixed stars is immensely distant, and that it is impossible to explain the motion of the planets upon the supposition of the earth being their centre. And he distinctly remarks: "It does not shame us to confess that the whole space in which the moon revolves, together with the earth, moves along a great orbit among the planets, round the sun every year; that the sun remains permanent and immovable, whatever may be its apparent motion." It must be kept in mind throughout any careful study of his theory, that it was an _hypothesis_ framed to remove difficulties connected with older systems; that he sought to bring conceptions of the universe into harmony with reason, instead of giving way to impressions made by the senses, or to the authority of world-honored teachers, either in other days or in his own; nor can we omit adding that, while he found fault with the Ptolemaic cycles and epicycles, he constructed similar devices of his own. "As the real motions, both of the earth and the planets, are unequable, it was requisite to have some mode of representing their inequalities; and accordingly the ancient theory of excentrics and epicycles was retained so far as was requisite for this purpose." In the case of Mercury's orbit he makes suppositions which are extremely complex, although they manifest his apprehension of the difficulties attendant on the common theory of his own time; but he verified many of his views by astronomical observations; and his approximations to modern science, and the light he threw on preceding discoveries, establish the fame of Nicholas Copernicus. On a review of the life of Copernicus, and the conclusions he reached, the mental and moral qualities of the man come out with conspicuous and extraordinary lustre.