The outside of a post-office before the opening of its doors reminds one of a vast sleeping city, cold and calm, though containing within itself all the elements that make up a living, sleepless world. As the stars shine down on the earth and move on in their spheres, so feeble lights gleam up from the post-office windows to denote that “watchers” of the night are there, and thus, like the machinery of the great world, move on the wheels of this epitomized one. Dull and heavy glide on the hours of night; silence like that of the prairie rests for a while on and around the city, save the howl of some watchful dog and the far-off sound of a tinkling bell. A city at night, wrapped in the curtains darkness throws around it, is like a vast sepulchre, and visited alike with ghosts from the _spirit_-world. Presently the dark panorama begins to move: there is an uprising of a long stream of light in the eastern sky; a vast and mysterious movement, as impulsive and as sudden as that of light, agitates the city; sounds quick and incessant come upon the ear,—rattling of wheels, ringing of bells: the world and its inhabitants are awake. The night dream is over; reality assumes its power once again. Moving on, men, women, and children take their respective ways to business or pleasure, for this world is made up of both. There you see the mechanic, there the merchant looking for the “early worm,” there the newsboy hurrying to his morning traffic in literature, himself its evil genius, there the housebreaker moving quietly away from the scene of his villany, and there the man of pleasure staggering to his wretched home. There is one point at which, however, many assemble: there, clustered around a marbled veneered building,—for it is not _all marble_,—you can read in the looks of the crowd the world’s history, and alike the name of the building: it is the PHILADELPHIA POST-OFFICE. The sun that awoke millions from their sleep now shines down and sheds its light around this “mimic world:” it awakes; its night slumber is over; the hour has arrived—action, action. The doors open—the crowd rush in. Ah! what is life?—one scene of struggle and strife, and for what? That’s the question. “Quid sit futurum eras fuge quærere” is not a bad idea of the poet Horace: its literal meaning is, “Avoid all inquiry with respect to what may happen to-morrow.” We should not look so anxiously into the future as to preclude all present enjoyment. Action, action is the motto of our land. This the effect of a cause,—that cause the Revolution. It changed alike men and the opinion of nations upon the subject of sovereignty. Mental, physical, political, speculative, and financial revolutions are all the results of one great cause,—a cause bearing date 1776. Here we are; here in the post-office, one of the branches of the General Government. This is the little world of letters, this the index to the inner history of man. It is a book of thoughts.