The subject of this paper is Georg Ernst Stahl's (1659-1734) reflections on epilepsy. In the German physician's work, the concept of disease is stratified: it is the morbid idea which causes dysfunctions in the animal economy, as well as irregular motion, overabundance and ultimately an alteration of the corporeal humours. In particular, epilepsy is an affection deriving from an altered functioning of the bodily motions, caused by abnormal blood flow, intestinal worms, anatomical defects, foreign bodies, and the passions of the soul. While a certain medical tradition attributed a nervous origin to epilepsy, Stahl, giving it a humoural genesis, openly shows the theoretical premises on which his physiology rests. So, Stahlian physiology appears to be a non-mechanistic, teleological-inspired, hydraulicism.