Despite this great mistake, still persistently believed in, and despite the crude notions of early astronomers on many points, it is marvelous how much they did manage to observe and to learn for themselves,--as to the sun and his apparent path, as to the moon and her path, as to the five then known planets and their paths, as to eclipses and other phenomena. By all such careful watching, although they to some extent missed their aim and fell into mistakes, yet they paved a way to later discoveries and to fuller knowledge. Their work was not thrown away, their trouble was not lost; for out of their very errors grew the fair form of truth. Nearly three hundred years after the time of Hipparchus came the famous Ptolemy--famous, not, like certain other astronomers, for stupendous genius, or for the brilliancy and accuracy of his observations, but rather noted for the ingenuity of his explanations, and for the adroit manner in which he systematized such knowledge, on the subject of the heavenly bodies, as was then in the possession of mankind. Ptolemy’s name is best known in connection with what is commonly called “The Ptolemaic System of the Universe,” and his greatest astronomical work is best known as the _Almagest_. A great many of Ptolemy’s leading notions, as well as the principal mass of facts upon which he worked, were doubtless borrowed from Hipparchus. The latter is said to have explained the movements of the sun and of the moon by means of small epicycles, traveling round the earth on circular orbits; and even Hipparchus did not originate this fundamental idea of the so-called “Ptolemaic System,” which had indeed been held by the ancients in much earlier days. Hipparchus worked it out to some extent, and Ptolemy carried on the process much farther, giving forth the system to the world in such wise that ever since it has gone by his name. The theory of cycles and epicycles lasted long--lasted from the time of Ptolemy in the second century to the time of Copernicus in the sixteenth century, of whom we have already spoken. [For about two thousand years, astronomers observed attentively the apparent revolutions of the heavenly bodies, and this attentive study gradually showed them a large number of irregularities and inexplicable complications, until at last they recognized that they were deceived as to the earth’s position, in the same way that they had been deceived as to its stability. The immortal Copernicus, in particular, discussed with perseverance the earth’s motion, already previously suspected for two thousand years, but always rejected by man’s self-love; and when this learned Polish canon bid adieu to our world in the year 1543, he bequeathed to science his great work, which demonstrated clearly the long-standing error of mankind.--_F._]