"Men," he says, "will always make mistakes, when they abandon experience for systems born of the imagination." Man exists in nature and can imagine nothing outside of nature. Let him, therefore, cease to seek beyond the world he inhabits for beings which shall procure for him that happiness which nature refuses to give him. "Man is a being purely physical. Moral man is but that being considered from a certain point of view, that is to say, relatively to some of his ways of acting, due to his particular organization." All human actions, visible and invisible, are the necessary consequences of man's mechanism, and of the impulsions which it receives from surrounding entities. The universe is made up of matter and motion, cause and effect. Nature is the great whole, resulting from the assemblage of different matters, combinations, and motions. By motion only do we know the existence and properties of other beings and distinguish them from each other. There is continual action and reaction in all things. Love and hate in men are like attraction and repulsion in physics, with causes more obscure. All beings, organic and inorganic, tend to self-preservation. This tendency in man is called self-love. There is in reality no order nor disorder, since all things are necessary. It is only in our minds that there exists the model of what we call order; like other abstract ideas, it corresponds to nothing outside of ourselves. Order is no more than the faculty of coordinating ourselves with the beings that surround us, or with the whole of which we form a part. But if we wish to apply the word to nature, it may stand for a succession of actions or motions which we suppose to contribute to a given end. We call beings intelligent when they are organized like ourselves, and can act toward an end which we understand.