Notes from Underground, Fyodor Dostoevsky

 You see, gentlemen, reason is an excellent thing, there's no disputing that, but reason is nothing but reason and satisfies only the rational side of man's nature, while will is a manifestation of the whole life, that is, of the whole human life including reason and all the impulses. And although our life, in this manifestation of it, is often worthless, yet it is life and not simply extracting square roots. Here I, for instance, quite naturally want to live, in order to satisfy all my capacities for life, and not simply my capacity for reasoning, that is, not simply one twentieth of my capacity for life. What does reason know? Reason only knows what it has succeeded in learning (some things, perhaps, it will never learn; this is a poor comfort, but why not say so frankly?) and human nature acts as a whole, with everything that is in it, consciously or unconsciously, and, even if it goes wrong, it lives. I suspect, gentlemen, that you are looking at me with compassion; you tell me again that an enlightened and developed man, such, in short, as the future man will be, cannot consciously desire anything disadvantageous to himself, that that can be proved mathematically. I thoroughly agree, it can—by mathematics. But I repeat for the hundredth time, there is one case, one only, when man may consciously, purposely, desire what is injurious to himself, what is stupid, very stupid—simply in order to have the right to desire for himself even what is very stupid and not to be bound by an obligation to desire only what is sensible. Of course, this very stupid thing, this caprice of ours, may be in reality, gentlemen, more advantageous for us than anything else on earth, especially in certain cases. And in particular it may be more advantageous than any advantage even when it does us obvious harm, and contradicts the soundest conclusions of our reason concerning our advantage—for in any circumstances it preserves for us what is most precious and most important—that is, our personality, our individuality.

(White Nights and Other Stories)