This research questions the existence, nature and role of the relationship between science and spirituality in the construction of scientific knowledge and, more generally, in the history of thought. To address this topic, we have chosen to examine the work of two spiritualist scholars: Isaac Newton and Georges Lemaître. These two figures set major landmarks in the history of science: the founding of celestial mechanics, the basis of modern science, and the founding of modern cosmology, which provided a radically new definition of the universe and of mankind's place within it. These two landmarks - one Newtonian and the other Lemaîtrian - go hand in hand, for one due to their shared subject: the whole, and also due to the subsequent succession and advancement in the history of science since they take us from the science of the sky, conceived as an absolute, to the science of the beginning and of cosmological evolution from general relativity. Our research into the two thinkers' philosophies shows that the relationship between science and spirituality is a dynamic, two-way relationship, a vital aspect of conceptual history, and more broadly of the history of thought. Moreover, it provides elements of synthesis and comparison between both scientists-philosophers and gives historical and philosophical rooting to the choice of subject. Our initial idea is thus supported and reinforced. Beyond the terms of the history of thought, our first approach consisted of understanding eminent actors in this history, understanding, through their ways of thinking, their being, their spirit, by their legacy in history.
