Homoia

work by Speusippus

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June 29, 2026

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Speusippus, Plato's successor as head of the Greek Academy, wrote Homoia ("Similitudes"). This work was a comparative study of plant and animal physiology. It has been favorably compared to Aristotle's History of Animals.1

Speusippus's philosophical views emphasized numbers and numerical combinations, deemphasizing ideas. He organized reality into spiritual spheres, inserting the soul between pure numbers and the physical world. While Aristotle criticized Speusippus, his Homoia suggests a view where classification and definition are interconnected, implying that one cannot define a single thing without considering all things.1

It is important to distinguish Homoia from homoousia (identity in essence or substance) and homoiousia (similarity but not identity in essence or substance).23

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Speusippus
…strongly criticized by Aristotle, his Homoia (“Similitudes”), a comparative study of plant and animal physiology, has been favourably compared with Aristotle’s own History of Animals and conceivably reflects Speusippus’ view that no single thing can be defined unless all are, because classification and definition are closely related.
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…strongly criticized by Aristotle, his Homoia (“Similitudes”), a comparative study of plant and animal physiology, has been favourably compared with Aristotle’s own History of Animals and conceivably reflects Speusippus’ view that no single thing can be defined unless all are, because classification and definition are closely related.
Read More