These same processes also occur in the human world. By _evolution_ must be understood the transformation that takes place day by day, which is almost unnoticed, but continuous and inevitable; by _revolution_, the critical and decisive period, more or less prolonged, of an evolution that has reached its concluding phase; by _rebellion_, the partially collective violence which breaks out, upon the occasion of some particular circumstance, at a definite place and time; and by _individual violence_, the action of one individual against one or several others, which may be the effect of a fanatical passion or of criminal instincts, or the manifestation of a lack of mental equilibrium,--and which identifies itself with the political or religious ideas most in vogue at the moment. It must be remarked, in the first place, that while revolution and evolution are normal functions of social physiology, rebellion and individual violence are symptoms of social pathology. These are, nevertheless, merely natural and spontaneous processes, since, as Virchow has shown, pathology is merely the sequel of normal physiology. Besides, the pathological symptoms have, or should have, a great diagnostical value for the classes in power; but the latter, unfortunately, in every period of history, in times of political crisis, as in those of social crisis, have shown themselves unable to conceive of any other remedy than brutal repression--the guillotine or the prison--and they fancy that thus they can cure the organic and constitutional disease which vexes the social body.[67] But it is indisputable, at all events, that the normal processes of social transformation (and because they are normal, the most fruitful and the surest, although the slowest and the least effective in appearance) are evolution and revolution, using the latter term in its accurate and scientific sense, as the concluding phase of an evolution, and not in the current and incorrect sense of a stormy and violent revolt.[68] It is evident, in fact, that Europe and America are, in these closing years of the nineteenth century, in a period of revolution, prepared by the evolution begotten by the bourgeois organization itself and promoted by utopian socialism as well as by scientific socialism. Likewise, we are in that period of social life which Bagehot calls "the age of discussion,"[69] and already we can see what Zola has called, in _Germinal_, the cracking of the politico-social crust, and, in fact, all those symptoms which Taine has described in his _l'Ancien Regime_, in relating the history of the twenty years which preceded 1789. As repressive methods are of no avail against domestic revolution, and only serve to expose the symptoms, there can be nothing efficacious and productive of good results, except laws of social reform and preparation which, while safe-guarding the present society, will render less painful, as Marx said, "the birth of the new society."