This creation, upon which everything else depended, dates from the time when Comte discovered _the law of the three states_ as it is called. For, once this law is established, “social physics” ceases to be a mere philosophical conception, and becomes a positive science. This law had been anticipated and even already formulated in the XVIII. century by Turgot, then by Condorcet, and by Dr. Burdin. Comte, nevertheless, takes to himself the merit of the discovery. As he is generally most precise in doing full justice to his “precursors,” we must admit that, according to him, none of them had seen the scientific importance of this law. It certainly is one thing to gather the notion of a law out of a number of facts, and another to understand its capital importance, and to discern in it the fundamental law which governs the whole of the evolution of humanity. This is the way in which Comte enounces it, in the _Plan des travaux scientifiques nécessaires pour réorganiser la société_ (1822). “According to the very nature of the human intellect every branch of our knowledge must necessarily pass successively in the course of its progressive development, through three different theoretical states: the theological or fictitious state, the metaphysical or abstract state, finally the scientific or positive state.”[12] In the first lesson of the _Cours de philosophie positive_, after having reproduced this statement, Comte adds: “In other words the human mind, by its nature, in each one of its researches makes use successively of three methods of philosophising, essentially different and even opposed to each other: firstly, the theological method, next, the metaphysical, and lastly the positive. Hence we find three kinds of philosophies, or general systems of conceptions of the totality of phenomena, which mutually exclude each other. The first is the necessary starting-point of human intelligence, the third, its fixed and final state; the second is solely destined to serve as a transition.”[13] The words “theological” and “metaphysical” are here taken in a particular sense, strictly defined.