[Sidenote: Its application to the solar system.]
In this manner the doctrine of government by law is extended, until at last it embraces all natural events. It was thus that, hardly two centuries ago, that doctrine gathered immense force from the discovery of Newton that Kepler's laws, under which the movements of the planetary bodies are executed, issue as a mathematical necessity from a very simple material condition, and that the complicated motions of the solar system cannot be other than they are. Few of those who read in the beautiful geometry of the 'Principia' the demonstration of this fact, saw the imposing philosophical consequences which must inevitably follow this scientific discovery. And now the investigation of the aspect of the skies in past ages, and all predictions of its future, rest essentially upon the principle that no arbitrary volition ever intervenes, the gigantic mechanism moving impassively in accordance with a mathematical law.
And so upon the earth, the more perfectly we understand the causes of present events, the more plainly are they seen to be the consequences of physical conditions, and therefore the results of law. To allude to one example out of many that might be considered, the winds, how proverbially inconstant, who can tell whence they come or whither they go! If any thing bears the fitful character of arbitrary volition, surely it is these. But we deceive ourselves in imagining that atmospheric events are fortuitous. Where shall a line be drawn between that eternal trade-wind, which, originating in well-understood physical causes, sweeps, like the breath of Destiny, slowly, and solemnly, and everlastingly over the Pacific Ocean, and the variable gusts into which it degenerates in more northerly and southerly regions--gusts which seem to come without any cause, and to pass away without leaving any trace? In what latitude is it that the domain of the physical ends, and that of the supernatural begins?
All mundane events are the results of the operation of law. Every movement in the skies or upon the earth proclaims to us that the universe is under government.
But if we admit that this is the case, from the mote that floats in the sunbeam to multiple stars revolving round each other, are we willing to carry our principles to their consequences, and recognise a like operation of law among living as among lifeless things, in the organic as well as the inorganic world? What testimony does physiology offer on this point?