Algebra. We received from them our numerical characters. We all know the beauty and permanence of their architecture, and much of our musical knowledge is derived from them. They also made great progress in scientific agriculture and horticulture, in mining and the working of metals, in tanning and dying leather. Damascus blades, morocco, enamelled steel, the manufacture and use of paper, the use of the pendulum, the manufacture of cotton, public libraries, a national police, rhyme in verse, and our arithmetic, all came to us from the Arabs. All this fruitful intellectual life must be traced directly back to the theological impulse given by Mohammed to the Arab mind; for it can be derived from no other source. It is not quite so easy to define the precise influence on human progress given by the doctrines of the Reformation; for, before Luther, these were in the air. But no one can reasonably doubt that the demand for freedom of conscience and the right of private judgment in religion has led to liberty of thought, speech, action, in all other directions. To the war against papal and ecclesiastical authority in concerns of the soul we owe, how much no one can say, of civil freedom, popular sovereignty, the emancipation of man, the progress of the human mind. The theses of Luther were the source of the Declaration of Independence. And modern science, with the great names of Bacon and Newton, Descartes and Leibnitz, Goethe and Humboldt, is the legitimate child of Protestant Theology. It is true that printing and maritime discoveries preceded Luther. But these inventions came from the same ideas which took form in the Lutheran Reformation. The discovery of printing was a result, no less than a cause. It came because it was wanted; because men were wishing to communicate their thoughts more freely and widely than could be done by writing. If it had been discovered five hundred years before, it would have fallen dead, a sterile invention, leading to nothing. And so the steam-engine and the railroad did not come before, because they were not wanted: as soon as they were wanted they came. That which lies at the root of all these inventions is the wish of man to communicate easily and rapidly and widely with his brother-man; in other words, the sense of human brotherhood. Material civilization, in all its parts and in all times, grows out of a spiritual root; and only faith leads to sight, only the things unseen and eternal create those which are seen and temporal.