From antiquity to the modern day, the wellbeing of body and soul and its man­agement is reliant upon fathoming the hidden: agents veiled by their inac­cessibility to immediate senses—such as viruses—or their existence beyond nature—such as spirits.

Greek humoral pathology was the dominant model adopted and revised in medieval Islam to interpret the physicality of health and its maintenance.^[851] However, the body, soul and mind are ontologically inextricable from the universe—the Macrocosm—and so physicality was not deemed independent from factors that are beyond the body and its immediate environment.

This paper will explore medieval Islamic ideas on spiritual aetiology and its connection with humoral pathology. The first part argues that diseasing ‘spirits' underwent an ontological metamorphosis as the paradigms of legiti­macy shifted from natural philosophy, based on a peripatetic understanding of causality and Neoplatonic notions of an animated universe, to religion and mysticism, spurred by the rise of traditionalism and the popularisa­tion and institutionalisation of Sufism in the twelfth and thirteenth centuries.^[852] Diseasing spirits morphed from cosmological pneumatic powers related to the influence of the stars to spirits in the conventional sense—‘demonic' and malicious—in the later period. The second part of this paper investigates spiritual therapeutics and the clash between two groups that claim to wield the right weapons against spirits: theologians armed with faith and occultists armed with their magical techniques.