“Differing in essences” does not simply mean varying in height, age or colour. Zayd and Amr may differ in those respects, yet both share the same human species-nature.
Human and horse differ at the level of species; animal is the generic nature shared between these different species.
Zayd, Amr, Khalid: distinct persons of one species.
Human, horse, sheep: distinct species under the genus animal.
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The Five Predicables: Genus, Species and Hierarchy of Genera
“Differing in essences” does not simply mean varying in height, age or colour. Zayd and Amr may differ in those respects, yet both share the same human species-nature.
Human and horse differ at the level of species; animal is the generic nature shared between these different species.
Zayd, Amr, Khalid: distinct persons of one species.
Human, horse, sheep: distinct species under the genus animal.