It is not always easy to explain the acceleration of certain sentiments under the influence of a constant exciting cause. Perhaps, however, one may say that if the laws of psychology are comparable to those of mechanics, a cause of invariable dimensions acting in a continuous fashion will rapidly increase the intensity of a sentiment. We know, for example, that a force which is constant in dimension and direction, such as gravity acting upon a mass, will cause an accelerated movement. The speed of a free object falling in space under the influence of gravity will be about 32 feet during the first second, 64 feet during the next, 96 feet during the next, &c. It would be easy, were the moving body allowed to fall from a sufficient height, to give it a velocity sufficient to perforate a plate of steel. But although this explanation is applicable to the acceleration of a sentiment subjected to a constant exciting cause, it does not tell us why the effects of acceleration finally and suddenly cease. Such a fall is only comprehensible if we bring in physiological factors--that is, if we remember that pleasure, like pain, cannot exceed certain limits, and that all sensations, when too violent, result in the paralysis of sensation. Our organism can only support a certain maximum of joy, pain, or effort, and it cannot support that maximum for long together. The hand which grasps a dynamometer soon exhausts its effort, and is obliged suddenly to let go. The study of the causes of the rapid disappearance of certain groups of sentiments in assemblies will remind us of the fact that beside the party which is predominant by means of its strength or prestige there are others whose sentiments, restrained by this force or prestige, have not reached their full development. Some chance circumstance may somewhat weaken the prevailing party, when immediately the suppressed sentiments of the adverse parties may become preponderant. The Mountain learned this lesson after Thermidor. All analogies that we may seek to establish between the laws of material phenomena and those which condition the evolution of affective and mystic factors are evidently extremely rough. They must be so until the mechanism of the cerebral functions is better understood than it is to-day. PART II THE FRENCH REVOLUTION BOOK I THE ORIGINS OF THE FRENCH REVOLUTION CHAPTER I THE OPINIONS OF HISTORIANS CONCERNING THE FRENCH REVOLUTION 1. The Historians of the Revolution. The most contradictory opinions have been expressed respecting the French Revolution, and although only a century separates us from the period in question it seems impossible as yet to judge it calmly. For de Maistre it was ``a satanic piece of work,'' and ``never was the action of the spirit of darkness so evidently manifested.'' For the modern Jacobins it has regenerated the human race. Foreigners who live in France still regard it as a subject to be avoided in conversation.