“A Knowledge of the construction of the heavens,” Herschel wrote in 1811, “has always been the ultimate object of my observations.” The “Construction of the Heavens”! A phrase of profound and novel import, for the invention of which he was ridiculed by Brougham in the Edinburgh Review; yet expressing, as it had never been expressed before, the essential idea of sidereal astronomy. Speculation there had been as to the manner in which the stars were grouped together; but the touchstone of reality had yet to be applied to them. This unattempted, and all but impossible enterprise Herschel deliberately undertook. It presented itself spontaneously to his mind-as worth the expenditure of a life's labour; and he spared nothing in the disbursement. The hope of its accomplishment inspired his early exertions, carried him through innumerable difficulties, lent him audacity, fortified him in perseverance. For this,

and burst his way into an unnavigated ocean.

Herschel has had very few equals in his strength of controlled imagination. He held the balance, even to a nicety, between the real and the ideal. Meditation served in him to prescribe and guide experience; experience to ripen the fruit of meditation.