Released in 1932, The Two Sources of Morality and Religion (The two sources) is Henri Bergson's last major work. There are many works devoted to the confrontation of his moral and social philosophy with Émile Durkheim's sociology. But these works don't explore his "mobilism" in The two sources. Reality is mobile. This is a recurring idea in his work from his Time and Free Will: An Essay on the lmmediate Data of Consciousness (published in 1889) to The two sources, where he asserts that open morality is mobility. Mobilism is essential to his moral philosophy. From this perspective, we propose to determine Bergson's position regarding the debate on the science of morals aroused by the work of Lucien Lévy-Bruhl (1903), Ethics and Morale science (La morale et la science des mœurs) in the year 1900. In this work, Lévy-Bruhl, inspired by Auguste Comte and Durkheim, seeks to establish an objective science of moral reality (which he called "science of morals") by adopting the sociological method, but by removing the "theoretical ethics", which don't observe morale reality, such as theological, utilitarian and Kantian ethics. If we locate The two sources in this historical context, Bergson's moral philosophy might appear as the third stage of moral thought, in relation to the first stage (theoretical ethics) and the second stage (science of morals). If such is the case, this third stage might be called "mobilism", which advances the research of moral reality? This is the assumption that this dissertation is investigating.