Although there are discoveries which are said to have been made by accident, if carefully inquired into, it will be found that there has really been very little that was accidental about them. For the most part, these so-called accidents have only been opportunities, carefully improved by genius. The fall of the apple at Newton’s feet has often been quoted in proof of the accidental character of some discoveries. But Newton’s whole mind had already been devoted for years to the laborious and patient investigation of the subject of gravitation; and the circumstance of the apple falling before his eyes was suddenly apprehended only as genius could apprehend it, and served to flash upon him the brilliant discovery then opening to his sight. In like manner, the brilliantly-coloured soap-bubbles blown from a common tobacco pipe—though “trifles light as air” in most eyes—suggested to Dr. Young his beautiful theory of “interferences,” and led to his discovery relating to the diffraction of light. Although great men are popularly supposed only to deal with great things, men such as Newton and Young were ready to detect the significance of the most familiar and simple facts; their greatness consisting mainly in their wise interpretation of them. The difference between men consists, in a great measure, in the intelligence of their observation. The Russian proverb says of the non-observant man, “He goes through the forest and sees no firewood.” “The wise man’s eyes are in his head,” says Solomon, “but the fool walketh in darkness.” “Sir,” said Johnson, on one occasion, to a fine gentleman just returned from Italy, “some men will learn more in the Hampstead stage than others in the tour of Europe.” It is the mind that sees as well as the eye. Where unthinking gazers observe nothing, men of intelligent vision penetrate into the very fibre of the phenomena presented to them, attentively noting differences, making comparisons, and recognizing their underlying idea. Many before Galileo had seen a suspended weight swing before their eyes with a measured beat; but he was the first to detect the value of the fact. One of the vergers in the cathedral at Pisa, after replenishing with oil a lamp which hung from the roof, left it swinging to and fro; and Galileo, then a youth of only eighteen, noting it attentively, conceived the idea of applying it to the measurement of time. Fifty years of study and labour, however, elapsed, before he completed the invention of his Pendulum,—the importance of which, in the measurement of time and in astronomical calculations, can scarcely be overrated. In like manner, Galileo, having casually heard that one Lippershey, a Dutch spectacle-maker, had presented to Count Maurice of Nassau an instrument by means of which distant objects appeared nearer to the beholder, addressed himself to the cause of such a phenomenon, which led to the invention of the telescope, and proved the