But here our plea for a purely rational basis for cultural laws, that is to say, for deriving them from social necessity, is interrupted by a sudden doubt. We have chosen as our example the origin of the murder prohibition. But does our account of it correspond to historical truth? We fear not; it appears to be merely a rationalistic construction. With the help of psycho-analysis we have studied this very point in the history of human culture, and supported by this study we are bound to say that in reality it did not happen like this. Even in men to-day purely reasonable motives are of little avail against passionate impulses. How much weaker, then, must they have been in the primordial animal man! Perhaps even now his descendants would still kill one another without inhibition, if there had not been among those acts of murder one—the slaughter of the primal father—which evoked an irresistible emotional reaction, momentous in its consequences. From it arose the commandment: thou shalt not kill, which in totemism was confined to the father-substitute, and was later extended to others, but which even to-day is not universally observed. But according to arguments which I need not repeat here, that primal father has been the prototype of God, the model after which later generations have formed their figure of God. Hence the religious explanation is right. God was actually concerned in the origin of that prohibition; his influence, not insight into what was necessary for society, brought it into being. And the process of attributing man’s will to God is fully justified; for men, knowing that they had brutally set aside the father, determined, in the reaction to their outrage, to respect his will in future. And so the religious doctrine does give us the historical truth, though of course in a somewhat remodelled and disguised form; our rational explanation belies it.