THE birth and death of worlds are ephemeral events in a cycle of astronomical time. In the life history of a stellar system, of a planet, of an animal, parallel periods of origin, exuberance, and of extinction are exhibited to our experience, or to our understanding. Man, in his material existence confined to a point, by continuity of effort and perpetuity of thought, becomes coequal and coextensive with the infinities of time and space. The intellectual store of ages has evolved the supremacy of the human race, but the zenith of its ascendancy may still be far off, and the aspiration after progress has been entailed on the heirs of all preceding generations. The advancement of humanity is the sum of the progress of its component members, and the individual who raises his own life to the highest attainable eminence becomes a factor in the elevation of the whole race. Familiarity with history dispels the darkness of the past, which is so prolific in the myths that feed credulity and foster superstition, the frequent parents of the most stubborn obstacles which have lain in the path of progress. The history of the past comprises the lessons of the future; and the successes and failures of former times are a prevision of the struggles to come and the errors to be avoided. The stream of human life having once issued from its sources, may be equal in endurance to a planet, to a stellar system, or even to the universe itself. The mind of the universe may be man, who may be the confluence of universal intelligence. The eternity of the past, the infinity of the present, may be peopled with races like our own, but whether they die out with the worlds they occupy, or enjoy a perpetual existence, transcends the present limits of our knowledge. From century to century the solid ground of science gains on the illimitable ocean of the unknown, but we are ignorant as to whether we exist in the dawn or in the noonday of enlightenment. The conceptions of one age become the achievements of the next; and the philosopher may question whether this world be not some remote, unaffiliated tract, which remains to be annexed to the empire of universal civilization. The discoveries of the future may be as undreamt of as those of the past, and the ultimate destiny of our race is hidden from existing generations.