Page:The Prose Works of Percy Bysshe Shelley (Volume 2).djvu/81

 above them, is to invent a second and superfluous hypothesis to account for what has already been accounted for by the laws of motion and the properties of matter. I admit that the nature of these laws is incomprehensible, but the hypothesis of a Deity adds a gratuitous difficulty, which so far from alleviating those which it is adduced to explain, requires new hypotheses for the elucidation of its own inherent contradictions.

The laws of attraction and repulsion, desire and aversion, suffice to account for every phenomenon of the moral and physical world. A precise knowledge of the properties of any object, is alone requisite to determine its manner of action. Let the mathematician be acquainted with the weight and volume of a cannon ball, together with the degree of velocity and inclination with which it is impelled, and he will accurately delineate the course it must describe, and determine the force with which it will strike an object at a given distance. Let the influencing motive, present to the mind of any person be given, and the knowledge of his consequent conduct will result. Let the bulk and velocity of a comet be discovered, and the astronomer, by the accurate estimation of the equal and contrary actions of the centripetal and centrifugal forces, will justly predict the period of its return.

The anomalous motions of the heavenly bodies, their unequal velocities and frequent aberrations, are corrected by that gravitation by which they are caused. The illustrious Laplace, has shewn, that the approach of the Moon