The varying impulses to which crowds obey may be, according to their exciting causes, generous or cruel, heroic or cowardly, but they will always be so imperious that the interest of the individual, even the interest of self-preservation, will not dominate them. The exciting causes that may act on crowds being so varied, and crowds always obeying them, crowds are in consequence extremely mobile. This explains how it is that we see them pass in a moment from the most bloodthirsty ferocity to the most extreme generosity and heroism. A crowd may easily enact the part of an executioner, but not less easily that of a martyr. It is crowds that have furnished the torrents of blood requisite for the triumph of every belief. It is not necessary to go back to the heroic ages to see what crowds are capable of in this latter direction. They are never sparing of their life in an insurrection, and not long since a general,[2] becoming suddenly popular, might easily have found a hundred thousand men ready to sacrifice their lives for his cause had he demanded it. [2] General Boulanger. Any display of premeditation by crowds is in consequence out of the question. They may be animated in succession by the most contrary sentiments, but they will always be under the influence of the exciting causes of the moment. They are like the leaves which a tempest whirls up and scatters in every direction and then allows to fall. When studying later on certain revolutionary crowds we shall give some examples of the variability of their sentiments. This mobility of crowds renders them very difficult to govern, especially when a measure of public authority has fallen into their hands. Did not the necessities of everyday life constitute a sort of invisible regulator of existence, it would scarcely be possible for democracies to last. Still, though the wishes of crowds are frenzied they are not durable. Crowds are as incapable of willing as of thinking for any length of time. A crowd is not merely impulsive and mobile. Like a savage, it is not prepared to admit that anything can come between its desire and the realisation of its desire. It is the less capable of understanding such an intervention, in consequence of the feeling of irresistible power given it by its numerical strength. The notion of impossibility disappears for the individual in a crowd. An isolated individual knows well enough that alone he cannot set fire to a palace or loot a shop, and should he be tempted to do so, he will easily resist the temptation. Making part of a crowd, he is conscious of the power given him by number, and it is sufficient to suggest to him ideas of murder or pillage for him to yield immediately to temptation. An unexpected obstacle will be destroyed with frenzied rage. Did the human organism allow of the perpetuity of furious passion, it might be said that the normal condition of a crowd baulked in its wishes is just such a state of furious passion.