Where has logic originated in men’s heads? Undoubtedly out of the illogical, the domain of which must originally have been immense. But numberless beings who reasoned otherwise than we do at present, perished; albeit that they may have come nearer to truth than we! Whoever, for example, could not discern the "like" often enough with regard to food, and with regard to animals dangerous to him, whoever, therefore, deduced too slowly, or was too circumspect in his deductions, had smaller probability of survival than he who in all similar cases immediately divined the equality. The dominant tendency however, to treat as equal that which is merely similar - an illogical tendency for there is nothing equal - is what first created the whole basis for logic. It was just so (in order that the conception of substance should originate, this being indispensable to logic, although in the strictest sense nothing actual corresponds to it) that for a long period the changing process in things had to be overlooked, and remain unperceived; the beings not seeing correctly had an advantage over those who saw everything "in flux" In itself every high degree of circumspection in conclusions, every sceptical inclination, is a great danger to life. No living being might have been preserved unless the contrary inclination to affirm rather than suspend judgment, to mistake and fabricate rather than wait, to assent rather than deny, to decide rather than be in the right had been cultivated with extra ordinary assiduity. The course of logical thought and reasoning in our modern brain corresponds to a process and struggle of impulses, which singly and in themselves are all very illogical and un just; we experience usually only the result of the struggle, so rapidly and secretly does this primitive mechanism now operate in us.