1 Corinthians 15:39

“All flesh is not the same flesh; but the flesh of men is one, the flesh of beasts another, that of birds another, that of fish another.”

Σάρξ, flesh, denotes the substance of the organism, and not merely its external form. In this series of examples, man is placed at the head; for, while belonging by his body to the animal kingdom, he alone of all living beings possesses the capacity of reaching a higher existence.

Κτήνη, strictly: cattle; a word coming from κτάομαι, to acquire, possess; here, no doubt, denoting all quadrupeds, among which cattle form the class nearest to man.

Πτηνά, birds; this class follows the preceding, perhaps by way of alliteration, the names of the two classes differing very little in Greek.

Fishes are put last, as being lowest in the scale.

These four classes may be united in a single group, that of terrestrial beings, to be contrasted with a higher group, celestial bodies. These latter differ from the former both in substance and splendour.