Herbert Spencer, James Mill, J. S. Mill, and Huxley popularized the agnostic standpoint. Spencer in his "First Principles" argues in this manner: "Those who cannot conceive of a self-existent Universe, and therefore assume a creator as the source of the Universe, take for granted that they can conceive a self-existent creator. The mystery which they recognize in this great fact surrounding them on every side, they transfer to an alleged source of this great fact, and then suppose that they have solved the mystery. But they delude themselves. Self-existence is inconceivable; and this holds true whatever be the nature of the object of which it is predicated. Whoever agrees that the atheistic hypothesis is untenable because it involves the impossible idea of self-existence, must perforce admit that the theistic hypothesis is untenable if it contains the same impossible idea.... If religion and science are to be reconciled, the basis of reconciliation must be this deepest, widest, and most certain of all facts, that the Power which the Universe manifests to us is inscrutable." Nietzsche, the great liberator of modern thought, vigorously opposed religious morality, the influence of Christianity, and all religious beliefs. "When the natural consequences of an action," he wrote, "are no longer looked upon as natural, but are considered to be produced by the phantasms of superstition, by 'God,' 'Ghosts,' and 'Souls,' and appear as 'moral' consequences, as rewards, punishments, guidance and revelation, then the whole basis of knowledge is destroyed; and the greatest possible crime against humanity has been committed." William James, claimed as a supporter of religion, argues that our inner experience makes us cognizant of a spiritual world. The advance of psychological research does not deal kindly with this contention, and such works as Leuba's "Psychology of Religious Mysticism" give a rational explanation of the mystic state. Moreover, James did not give his support to monotheism. "That vast literature of proofs of God's existence," he stated, "drawn from the order of nature, which a century ago seemed so overwhelmingly convincing, today does little more than gather dust in the libraries, for the simple reason that our generation has ceased to believe in the kind of God it argued for. Whatever sort of God may be, we know today that he is nevermore that mere external inventor of 'contrivances' intended to make manifest his 'glory' in which our great-grandfathers took such satisfaction." James claimed to be a pluralist in the sense that there are several or many spiritual beings above us, and his writings lead one to believe that he was not convinced that man, as a distinct personality, survives the grave.