According to d’Holbach, nature is a great chain of causes and effects. Nature is the great whole, comprising everything visible and invisible. Baron d’ Holbach gives the laws of the physical world based on laws of motion and gravitation, as given by Newton, and he wants to apply the law of attraction and repulsion in the field of morality. All knowledge comes through the sense organs created by the impressions of the world and deposited in the brain, which is the real seat of thought.
Man searches for happiness in this world, but the priesthood misguides the people by asking them to look for happiness in future life, as guided by the chimeras of religion. Man living in society should be guided by reason, experience, and sciences by working for his happiness and contributing to the happiness of other members of the society by his hard work, talent, and virtues, by being useful to others by satisfying their needs while satisfying his own needs. Happiness is on this earth, and by reason and experience, he can be happy, and not as the priesthood preaches in another future life.