So accustomed are we, however, to consider the nature and limits of the different sciences, as depending on the objects themselves, and not on the laws of the mind, which classes their relations, that it may be difficult for you at first to admit the influence of these mere laws of mind, as modifying general physics, at least to the extent which I have now stated. But, that a change in the laws of human thought, whatever influence it might have in altering the very nature and limits of the physical sciences, would at least affect greatly the state of their progress, must be immediately evident to those who consider for a moment on what discovery depends; the progress of science being obviously nothing more than a series of individual discoveries, and the number of discoveries varying with the powers of the individual intellect. The same phenomena which were present to the mind of Newton, had been present, innumerable times before, not to the understandings of philosophers only, but to the very senses of the vulgar. Every thing was the same to him and to them, except the observing and reasoning mind. To him alone, however, they suggested those striking analogies, by which on a comparison of all the known circumstances in both, he ventured to class the force which retains the planets in their orbits, with that which occasions the fall of a pebble to the earth. “Have ye not listen'd, while he bound the suns And planets to their spheres! the unequal task Of human kind till then. Oft had they roll'd O'er erring man the year, and oft disgraced The pride of schools. ----He took his ardent flight Through the blue infinite; and every star Which the clear concave of a winter's night Pours on the eye, or astronomic tube, Far-stretching, snatches from the dark abyss, Or such as farther in successive skies To fancy shine alone, at his approach Blazed into suns, the living centre each Of an harmonious system; all combined, And ruled unerring by that single power, Which draws the stone projected to the ground.”[5]