Given the account that I give of natural kind terms in Aristotle, the task of explaining the coherence of essentialist claims lay elsewhere for him than in the theory of reference. He required a deeper account of necessity and explanation than the modern theorist provides in order to fulfill an explanatory task left virtually untouched by his account of the meaning of these terms. ... The ancient and modern routes to essentialism seem fundamentally different. And this is why Aristotle did not require to attribute to the pre-scientific thinker the deep assumptions invoked by the modern theorist.
Charles, David, "Aristotle on Meaning and Natural Kinds" (1986). The Society for Ancient Greek Philosophy Newsletter. 93.