The young souls of mankind must receive the comparatively simple lessons of sensation, desire, and passion, before beginning the far more complicated study of mentality. But for desire, a host of needs could not be manifested, numberless functions would remain inactive; the body would not feed itself, and would die, were it not for hunger; danger would not be fled from, but for the instinct of self-preservation; nor without this would there be any propagation of the species. None the less is this life of sensation the source of many evils; desire and passion amongst human beings create terrible misery, fill prisons and hospitals, and are at the root of all kinds of moral suffering. In its turn, intelligence--that sensation so characteristic of the human state--is both an indispensable necessity and the most fertile source of evil, so long as it has not experienced a yearning for that inner "divinity," deep in the heart of man, which calls to it. A powerful lever of progress, it might convert this earth into a paradise, whereas it is the weapon which the strong, in their egoism, use to crush the feeble, a terrible weapon which either creates or intensifies all the evils under which the people writhe in despair. Once it becomes the instrument of a regenerate humanity, that is to say, when men have become compassionate, loving, and devoted, then the social question will cease to exist, and the old instrument of torture will become a pledge of general happiness. Even spiritual sensibility is a cause of suffering to some noble souls who have developed it, for however deep the joy of loving and giving oneself, intense too is the pain of witnessing the cruel drama of life, that fratricidal struggle in which passion strikes without mercy, whilst illusion and ignorance deal blows even more terrible, for into the wounds they make they instil the poison of revolt and despair.