"L'Action" (1893) is considered Blondel's main work. In this essay, he methodically and thematically unfolds the fundamental principles of a new way of thinking. He replaces the 'is' sign in the equation of Parmenides with action, as abstract thinking can never fully grasp concrete life reality. Only through our actions can we mutually engage with concrete reality and achieve fulfillment. Action is the universal concrete, the ultimate bond and link. All aspects of human life and the entirety of reality are immanent to action as their elements. Blondel unfolds these elements in a serial manner within a comprehensive philosophy of will. He explicitly approaches this phenomenologically. What follows from the mere fact that the will wills? In doing so, he also demonstrates that religious action is philosophically undeniable.