But Catholic monotheism could not escape dissolution. The metaphysical spirit began to operate powerfully on the notions of moral philosophy, as soon as the Catholic organisation was complete; and Catholicism, because it could not assimilate this intellectual movement, lost its progressive character and stagnated. The decay began in the fourteenth century, where Comte dates the beginning of the Metaphysical period--a period of revolution and disorder. In the fourteenth and fifteenth centuries the movement is spontaneous and unconscious; from the sixteenth till to-day it has proceeded under the direction of a philosophical spirit which is negative and not constructive. This critical philosophy has only accelerated a decomposition which began spontaneously. For as theology progresses it becomes less consistent and less durable, and as its conceptions become less irrational, the intensity of the emotions which they excite decreases. Fetishism had deeper roots than polytheism and lasted longer; and polytheism surpassed monotheism in vigour and vitality. Yet the critical philosophy was necessary to exhibit the growing need of solid reorganisation and to prove that the decaying system was incapable of directing the world any longer. Logically it was very imperfect, but it was justified by its success. The destructive work was mainly done in the seventeenth century by Hobbes, Spinoza, and Bayle, of whom Hobbes was the most effective. In the eighteenth all prominent thinkers participated in developing this negative movement, and Rousseau gave it the practical stimulus which saved it from degenerating into an unfruitful agitation. Of particular importance was the great fallacy, which Helvetius propagated, that human intellects are equal. This error was required for the full development of the critical doctrine. For it supported the dogmas of popular sovranty and social equality, and justified the principle of the right of private judgement.