As in determining the function of Government, so here again is the necessity of knowledge. Man must know himself, and that law of Unity appointed for the Human Family. Such is the true light for our steps. Here are guidance and safety. Who can measure the value of knowledge? What imagination can grasp its infinite power? As well measure the sun in its glory. The friendly lamp in our streets is more than the police. Light in the world is more than armies or navies. Where its rays penetrate, there has civilization begun. Not the earth, but the sun, is the centre of our system; and the noon-day effulgence in which we live and move symbolizes that other effulgence which is found in knowledge. Great powers are at hand, ministers of human progress. I name two only: first, the printing-press; and, secondly, the means of intercommunication, whether by navigation or railways, represented by the steam-engine. By these civilization is extended and secured. It is not only carried forward, but fixed so that there can be no return,--like the wheel of an Alpine railway, which cannot fall back. Every rotation is a sure advance. Here is what Greece and Rome never knew, and more than Greece and Rome have contributed to man. By the side of these two simple agencies how small all that has come to us from these two politest nations of Antiquity! We can better spare Greece and Rome than the printing-press and steam-engine. Not a triumph in literature, art, or jurisprudence, from the story of Homer and the odes of Horace to the statue of Apollo and the bust of Augustus, from the eloquence of Demosthenes and Cicero to that Roman Law which has become the law of the world, that must not yield in value to these two immeasurable possessions. To the printing-press and steam-engine add now their youthful handmaid, the electric telegraph, whose swift and delicate fingers weave the thread by which nations are brought into instant communion, while great cities, like London and Paris, New York and San Francisco, become suburbs to each other, and all mankind feel together the throb of joy or sorrow. Through these incomparable agencies is knowledge made coextensive with space and time on earth. No distance of place or epoch it will not pervade. Thus every achievement in thought or science, every discovery by which Man is elevated, becomes the common property of the whole Human Family. There can be no monopoly. Sooner or later all enjoy the triumph. Standing on the shoulders of the Past, Man stands also on the shoulders of every science discovered, every art advanced, every truth declared. There is no height of culture or of virtue--if virtue itself be not the highest culture--which may not be reached. There is no excellence of government or society which may not be grasped. Where is the stopping-place? Where the goal? One obstacle is overcome only to find another, which is overcome, and then another also, in the ascending scale of human improvement.