In the mind of Herschel imagination and observation were marvellously blended. He was a philosophical astronomer. Although his imagination was a very vivid one he did not allow his fancies to run away with him, as Kepler sometimes did: on the other hand, he did not, like Flamsteed, refrain from speculating altogether. “We ought,” he wrote in 1785, “to avoid two opposite extremes. If we indulge a fanciful imagination, and build worlds of our own, we must not wonder at our going wide from the path of truth and nature. On the other hand, if we add observation to observation, without attempting to draw not only certain conclusions but also conjectural views from them, we offend against the very end for which only observations ought to be made.” These characteristics—the lightness with which he held his theories, his vivid imagination, and his philosophical reasoning—are the secrets of Herschel’s success as an astronomer. Nearly all his ideas and speculations have been confirmed. As Arago has said, “We cannot but feel a deep reverence for that powerful genius that has scarcely ever erred.” Herschel, like all other great students of Nature, was deeply religious. He could not observe the heavens without feeling awed at the marvels which his telescopes revealed. In his own words, “It is surely a very laudable thing to receive instruction from the Great Workmaster of Nature.” Friedrich Wilhelm Herschel, born in Hanover on November 15, 1738, was the fourth child of Isaac Herschel, an oboist in the band of the Hanoverian Guard. Isaac Herschel, a native of Dresden, was an accomplished musician, and all his children, ten in number, inherited his talent. Of these ten, six survived, and only two became famous. These were William, the great astronomer, and his sister Caroline (born on March 16, 1750), who became a student of the heavens only second to her brother. At the garrison school in Hanover, where the Herschels were educated, William Herschel showed intense love and aptitude for learning, and was more diligent and persevering than his brother Jacob, his senior by four years. In 1753 he became oboist in the band of the Hanoverian Guard in which his father was now bandmaster. In her valuable memoirs, his sister relates that her father was very interested in astronomy, and that he taught his children the names of the constellations. William became devoted to the science, and constructed a small celestial globe on which equator and ecliptic were engraved. But his studies were much hampered. His mother had a great dislike to learning: she had no sympathy with aspirations, and tried to prevent her children becoming well educated. Above all, the Hanoverian Guard was ordered to England in 1755, when a French invasion was feared, and to that country Herschel proceeded, along with his father and brother.