The question is not how long this bodily life may last, or how long the mind, so conditioned, can endure. It is not even how long the mind may continue to produce; for the mind, like a poor, half-exhausted field, urged with rain and fertilizers, may produce only potatoes, mullen, and cockle. The real question--the deep-down essence of it--is how long the mind, or soul, may retain the enthusiasm and passionate power of _creation_. That is the only true test of longevity; and when that ceases there is nothing left. The real duration of man-life is measured only by the persistency of creative power. Longfellow, standing in the old pulpit, on the fiftieth anniversary of his class at Bowdoin, and saying to those who would introduce him, "I wish the desk were large enough to conceal me all," makes a beautiful section of this theme by citing some of the most inspiring instances of the long life of the soul: Cato learned Greek at eighty; Sophocles Wrote his grand OEdipus, and Simonides Bore off the prize of verse from his compeers, When each had numbered more than fourscore years; And Theophrastus at fourscore and ten Had but begun his "Characters of Men;" Chaucer at Woodstock with his nightingales, At sixty wrote the Canterbury Tales; Goethe at Weimar, toiling to the last, Completed Faust when eighty years were past: These are indeed exceptions; but they show How far the Gulf Stream of our youth may flow Into the arctic regions of our lives, Where little else than life itself survives. Measured by this test of creative power and its persistency, how variable is the duration of human life! Sometimes the creative power appears in early youth; but when that happens there is generally an early surcease. Sometimes the power comes late and remains long. Sometimes it flashes forth in the early morning and remains in the after twilight. Estimated by years this productive power (which goes by the name of genius) sometimes reaches only to a few score moons. Sometimes it reaches to a score of years. Sometimes, though rarely, it extends to three-score years or more. Thomas Chatterton went to a suicide's grave in Potter's Field when he was only seventeen years, nine months, and four days of age. I know of no other case of so great precocity; it is beyond belief. His mind had been productive for about three years. Byron's productive period covered sixteen years--no more. Pope began at twelve and ended at fifty-six. In our own age, Tennyson has done well. Making an early effort to begin, he, like Dryden, did not really reach the creative epoch until he was fully thirty. His creative period covers about fifty-nine years. It extends from "A Dream of Fair Women," in 1833, to "Crossing the Bar," in 1892.