Nature has made men neither good nor bad; it has made them machines. Man is virtuous only in obedience to the call of interest. Morals are founded on our approbation of those actions which are advantageous to the race. When good actions benefit others and not ourselves our approbation of them is similar to the admiration we feel for a fine picture belonging to some one else. The good man is he whose true ideas have shown him that his happiness lies in a line of conduct which others are forced by their own interests to like and approve. By virtue we acquire the good will of our neighbors, and no man can be happy without it. Our self-love becomes a hundred times more delightful when to it is joined the love of others for us. Let us remember that the most impracticable of all designs is that of being happy alone.
To this point in his argument Holbach had only repeated with strength, clearness and consistency what the school of the Philosophers from Voltaire to Helvetius had either affirmed or hinted. In his second volume, however, he boldly cut loose from his predecessors and avowed his disbelief in any God. Voltaire and Rousseau were theists, with different sorts of faith, and the Philosophers, although treating all churches, and especially all priests, with contempt, had retained, at least in speech, some remnant of theism. But Holbach declared that God was an illusion, devised by the fears and the ignorance of mankind. "The idea of Divinity," he says, "always awakens afflicting ideas in our minds. "By the word "God" men mean the most hidden or remote cause; they use the word only when the chain of material and known causes ceases to be visible to them. It is a vague name which they apply to a cause short of which their indolence, or the limits of their knowledge, forces them to stop. Men found nature deaf to their cries; they therefore imagined an intelligent master over it, hoping that he would listen to them.
This theme is elaborated by Holbach throughout his second volume. Here as elsewhere he writes with seriousness and conviction, although some of his logical positions are assailable. Never before in France had materialism, necessarianism and atheism been so clearly and forcibly expounded. The very Philosophers were alarmed. Voltaire hastened to write an article on God so unconvincing, that it can hardly have convinced himself. It amounts to little more than an argument that God is the most probable of hypotheses, and it admits that there may be two or several gods as well as one. It is not unlikely that Voltaire thought it necessary for his peace in the world to protest against so outspoken a book as the "System of Nature."