are found the most useful—such as common sense, attention, application, and perseverance. Genius may not be necessary, though even genius of the highest sort does not disdain the use of these ordinary qualities. The very greatest men have been among the least believers in the power of genius, and as worldly wise and persevering as successful men of the commoner sort. Some have even defined genius to be only common sense intensified. A distinguished teacher and president of a college spoke of it as the power of making efforts. John Foster held it to be the power of lighting one's own fire. Buffon said of genius "it is patience."
Newton's was unquestionably a mind of the very highest order, and yet, when asked by what means he had worked out his extraordinary discoveries, he modestly answered, "By always thinking unto them." At another time he thus expressed his method of study: "I keep the subject continually before me, and wait till the first dawnings open slowly by little and little into a full and clear light." It was in Newton's case, as in every other, only by diligent application and perseverance that his great reputation was achieved. Even his recreation consisted in change of study, laying down one subject to take up another. To Dr. Bentley he said: "If I have done the public any service, it is due to nothing but industry and patient thought." So Kepler, another great philosopher, speaking of his studies and his progress, said: "As in Virgil, 'Fama mobilitate viget, vires acquirit eundo,' so it was with me, that the diligent thought on these things was the occasion of still further thinking; until at last I brooded
