How many of all our joys and sorrows, our loves and hates, our good and evil actions, spring from physical causes only? Even material substances display moods and affections, as when heated, electrified, decomposed, or set in motion; the sea at rest presents a different mood from the sea raging. Jean-Jacques Rousseau's idea that the soul might be governed for its good by material things working through the media of the senses, is not so extravagant after all. "The gospel according to Jean-Jacques," as Carlyle puts it, runs as follows on this point--and, indeed, the great Genevan evangelist at one time intended to devote a book to the subject under the title of _La Morale Sensitive_:--"The striking and numerous observations that I had collected were beyond all dispute; and, in their physical origin, they appeared to me proper for furnishing an exterior regimen, which, varied according to circumstances, should be able to place or maintain the soul in the state most favorable to virtue. How many wanderings one might save the reason, how many vices might be hindered birth, if one could but force the animal economy to favor the moral order that it troubles so often. Climates, seasons, sounds, colors, darkness, light, the elements, food, noise, silence, movement, repose, all act on our bodily frame, and, by consequence, on our soul; all offer us a thousand firm holds to govern, in their origin, those sentiments by which we allow ourselves to be dominated." In contemplating the numerous activities by which we are surrounded, again and again we are called upon to wonder at the marvelous regularity which characterizes all their movements. So regular are these movements, so sure are certain conditions to accompany certain results, that in physics, in chemistry, in physiology, and even in society, facts are collected and classified, and from them laws are discovered as fixed and irrevocable as the facts themselves, which laws, indeed, are themselves facts, no less than the facts from which they are deduced. Highly cultivated nations frame laws that provide for many contingencies, but the code of nature has yet finer provisions. There are conditions that neither political nor social laws reach, there are none not reached by physical law; in society, criminals sometimes evade the law; in nature, never. So subtle are the laws of nature, that even thought cannot follow them; when we see that every molecule, by virtue of its own hidden force, attracts every other molecule, up to a certain point, and then from the same inherent influence every atom repels every other atom; when by experiments of physicists it has been proved that in polarization, crystallization, and chemical action, there is not the slightest deviation from an almost startling regularity, with many other facts of like import, how many natural laws do we feel to be yet unrevealed and, from the exquisite delicacy of their nature, unrevealable to our present coarse understanding.