Our doctoral research investigates the place of disease and health in Leibnizian thought, particularly in the deployment of his epistolary work; understands how health and disease are part of a philosophical system that considers the unity of corporeal substance to be indivisible; and, indicates how the understanding of the health-disease relationship shows Leibniz's constant inclination to point out the need to transform medical art into scientific knowledge. In this sense, we want to show that Leibniz's concern for the issues of nature, life, living beings and their care, should allow us to frame his correspondence with the doctors of the time in the light of certain writings from the Leibnizian corpus such as Theodicy Essays, Considerations on the principles of life, De Ipsa Natura, Monadology, just to mention some of the mandatory reading texts. With this in mind, we examine the controversy that our German philosopher had with the doctor Georg Stahl and, we end with a review of the epistolary exchange that Leibniz had with rulers, doctors and intellectuals of the moment, trying to show that the notions of health, disease and medicine played a fundamental part in his philosophical and scientific reflections. This review is made with the purpose of showing how the understanding of the relationship between health and disease exposes the fragility of organic bodies and how, at the same time, the health-disease link is part of the conformation of the corporeal substance, since it is inherent in its indivisible unity. Likewise, we show that concern for these issues is a social matter and not a purely individual one, since it must be part of public order discussions for the scientific, social and cultural progress of a nation. Therefore, taking a philosophical interest in the issues of medical knowledge implies framing them in an integral perspective of human life and, for this reason, indicates at the same time the horizon with which the object of study of medicine can be approached. In this sense, the theoretical fruit of medicine to advance as a science is the knowledge of bodies, dealing with the conservation and care of human life in order to promote the common well-being.