Among the vitalisms, the school of Montpellier, following Paul-Joseph Barthez (1734-1806), proposed a theoretical approach of life : given that all vital manifestations are caused by a Vital principle, unknown in its nature but suitable for the elaboration of a specific science, the Science de l'Homme, this « philosophical » vitalism is a kind of logical construction, of abstract calculation.

Barthez's heir, Jacques Lordat (1773-1870), extended this point of view by the elaboration of a medical Anthropology : man being composed of soul, vital principle and material elements, what matters is the relation between these three components. Lordat applied this approach in different fields, using a combination of clinical, physiological, literary, philosophical or artistic data : « aphasiology » (language disorders), anesthesiology...

In his Physiological theory of human passions (Théorie physiologique des passions humaines), published in 1853, Lordat defined passions as an unusual and temporary mode of the human complex (as defined above), associating a pathetic idea in soul and an abnormal local sensation derived from the Vital principle, the initial cause being possibly located in both. As usual, Lordat ascertained this definition by arguments obtained from the different fields of human knowledge, providing a very original insight for his time. Far from a strictly experimental point of view, his logical theory appears simultaneously as anachronic and open to subsequent developments.