and the relation of medicine to the human body is one and the same. Hence one may say, “The king and the soul are one,” that is, in respect of this relation. These four unities—unity in genus, species, accident, and relation—are all covered by our expression “unity of kind,” indeed by “unity of genus,” for the words jins (genus), ṣinf (class), nawʿ (species/kind), ʿaraḍ (accidental attribute), and similar terms are synonymous in Arabic. The same is true in common Arabic usage of words like ḍarb and namaṭ and many others.

Al-Jawharī (1) says: “Jins: a class (ḍarb) of a thing, and it is broader than nawʿ; from it come the words mujānasa and tajnīs. Ibn Durayd alleged that al-Aṣmaʿī used to reject the common saying, ‘this is mujānis to that,’ maintaining that it was a coined expression” (2). He also said: “Ḍarīb (3) of a thing means its like and counterpart; ḍarāʾib are its similars” (4). And he said as well: “Ṣinf: species or kind (nawʿ and ḍarb); the form ṣanf with the first vowel open is also an attested pronunciation” (5).

Thus, at times he treats nawʿ as more specific than jins, while at other times he equates jins with ḍarb and makes ṣinf identical with nawʿ and ḍarb, so that jins, nawʿ, ḍarb, and ṣinf all mean the same thing—this is the original usage in the language. As for the view that species (nawʿ) is the more specific term, that is merely a later technical convention, not part of the language’s original core.