During a long conversation with Hakim Zillurrahman at his residence in Aligarh in 2012, I asked him to define Unani medicine in one single sentence. He began talking about the temperaments and the four humours and their importance as they constitute the basis of Unani. He explained that they are central because through their observation, a physician can establish the cause of the disease, and knowing the cause is crucial for the selection of appropriate treatment. Hakim Zillurrahman argued that excess of one humour caused imbalance and that, when there is imbalance, the human body becomes susceptible to disease. Unlike in allopathy, he went on, in Unani medicine there is the idea that disease is caused by the dominance of one humour. Therefore, the line of treatment has to address that excess humour. Medicines give the body t̤āqat (‘strenght’) to heal itself. Therefore, he stressed, the cause of disease has a central role in Unani, and this is the main idea on which the system is based. Now, if Unani had to be defined in one sentence, he would say temperaments, humours, and arkān (‘elements’), as the system is based on them. ‘That is Unani identity, because there is no other system based on the four humours and addressing the issue of cause of disease’, he concluded.

Hakim Zillurrahman's emphasis on elements, temperaments, and especially humours as Unani's identity reflected the answers given by hakims and Unani graduates when asked what Unani medicine is. Similarly, the scholarly study of Unani medicine has been characterized by representing Unani as a humoural form of medicine. In their study of Medieval Graeco-Islamic medicine, Peter Pormann & Emilie Savage-Smith argued that ‘[t]he single most pervasive explanatory medical principle was that of humoral pathology inherited from the Greeks’ (2007: 43). The understanding of humoural balance in the body as a healthy state and that of humoural imbalance as disease was attributed to Hippocrates (Pormann and Savage-Smith 2007: 9) and embodied the ambivalent relationship between Unani medicine and Western science: on the one hand, humouralism stood as evidence of a common origin and, as such, of a strong historical connection between both. On the other hand, it materialized the breach between Unani and Western science from the nineteenth and twentieth centuries based on the rejection of humouralism through the emergence of modern science and the discovery of the germ theory.