That is why irony and sarcasm prove to be a necessary weapon of the investigator. The most dangerous enemy of new knowledge always has been, and always will be, inculcated habit. From the practical point of view it is much more important to a man to know the things which may help him to adapt himself to the temporary conditions of his existence, than those which have a timeless value. The instinct of self-preservation always proves stronger than the sincerest desire for knowledge. Moreover, one must remember that the instinct has at its disposal innumerable and most subtle weapons of defence, that all human faculties without exception are under its command, from unconscious reflexes up to the enthroned mind and august consciousness. Much and often has been said in this regard, and for once the _consensus sapientium_ is on my side. True, this is treated as an undeniable perversion of human nature--and here I make my protest. I think that there is in this nothing undesirable. Our mind and consciousness must consider it an honour that they can find themselves in the service of instinct, even if it be the instinct of self-preservation. They should not be conceited, and to tell the truth they are not conceited, but readily fulfil their official mission. They pretend to priority only in books, and tremble at the thought of pre-eminence in life. If by some accident they were allowed freedom of action they would go mad with terror, like children lost in a forest at night. Every time that the mind and consciousness begin to judge independently, they reach destructive conclusions. And then they see with surprise that this time too they were not acting freely, but under the dictation of the self-same instinct, which had assumed a different character. The human soul desired the work of destruction, and she loosed the slaves from their chains, and they in wild enthusiasm began to celebrate their freedom by making great havoc, not in the least suspecting that they remained just as they were before, slaves who work for others.