D'Holbach's objectives in challenging religion were primarily moral: He saw the institutions of Christianity as a major obstacle to the improvement of society. For him, the foundation of morality was to be sought not in Scripture but in happiness: "It would be useless and almost unjust to insist upon a man's being virtuous if he cannot be so without being unhappy. So long as vice renders him happy, he should love vice." D'Holbach's radicalism posited that humans were fundamentally motivated by the pursuit of enlightened self-interest, which is what he meant by "society," rather than by empty and selfish gratification of purely individual needs. Chapter 15 of Part I of "System of Nature" is titled "Of Man's true Interest, or of the Ideas he forms to himself of Happiness.--Man cannot be happy without Virtue."