Ibn Sīnā (Avicenna) brought the most widely distributed Arabic philosophy on the topic, building on Greek writings but synthesized in different ways. This stream built on humoral theory, which held that an individual’s sexual expression resulted from their balance of qualities (hot, cold, wet, dry). Although this balance generally resulted in distinct categories of male and female (with their associated behavioral and social features), it also allowed for intermediate forms.

– Heather Rose Jones, Historic Classification of Sexual Ambiguity (discussing Chapter 4, The Shape of Sex) https://alpennia.com/blog/historic-classification-sexual-ambiguity (intersex-phobia and sexism discussed)