The Presocratic case for hylozoism grew directly out of observations that seemed to blur the line between the living and the inert: Thales pointed to the magnet's power to move iron and the amber's power to attract light objects when rubbed as evidence that matter itself has a capacity for self-motion, which the Greeks took as close to the definition of soul. Anaximenes, treating air as the underlying substance of everything, held that the same air that constitutes the soul also constitutes the whole cosmos, making the world quite literally a breathing, ensouled body.
Paracelsus took the idea into Renaissance medicine and alchemy, arguing that plants, minerals, and metals each carry their own inner vital principle and correspond to processes in the living human body, so that healing worked by matching the living force in a remedy to the living force in the patient rather than by mechanically countering a symptom.
The mechanist reaction, beginning with Descartes's picture of animal bodies as complex machines, treated all of this as a category error: matter, on the mechanist view, has no inner life at all, and what looks like vitality is really just complex physical arrangement, a criticism that became the dominant scientific consensus by the nineteenth century and effectively ended hylozoism's standing as a live option in mainstream physiology.