Vasilis Politis is Professor of Philosophy at Trinity College Dublin. He is author of numerous books, including The Structure of Enquiry in Plato's Early Dialogues (Cambridge, 2015) and The Aporetic Tradition in Ancient Philosophy (with George Karamanolis, Cambridge, 2018).

• Introduction; 1. Why Cannot the ti esti Question Be Answered by Example and Exemplar? Hippias Major; 2. Why Cannot Essences, or Forms, be Perceived by the Senses? Hippias Major. Phaedo. Republic; 3. Why are Essences, or Forms, Unitary, Uniform and Non-Composite? Why are they Changeless? Eternal? Are they Logically Independent of Each Other? Phaedo and Republic; 4. The Relation between Knowledge and Enquiry in the Phaedo; 5. Why are Essences, or Forms, Distinct from Sense-Perceptible Things? Phaedo 74 and Republic V. 478–479; 6. Why are Essences, or Forms, the Basis of all Causation and Explanation? Phaedo 95–105; 7. What is the Role of Essences, or Forms, in Judgements about Sense-Perceptible and Physical Things? Republic VII. 523–525; 8. Why does Thinking of Things Require Essences, or Forms? Parmenides; 9. Why are Essences, or Forms, Separate from Physical Things? Also Timaeus and Philebus; 10. What Yokes Together Mind and World? Phaedo 99–100 and Republic VI. 505–509; Conclusion: Forms Simply are Essences, not Things that have Essences.

Vasilis Politis is Professor of Philosophy at Trinity College Dublin. He is author of numerous books, including The Structure of Enquiry in Plato's Early Dialogues (Cambridge, 2015) and The Aporetic Tradition in Ancient Philosophy (with George Karamanolis, Cambridge, 2018).

• Introduction; 1. Why Cannot the ti esti Question Be Answered by Example and Exemplar? Hippias Major; 2. Why Cannot Essences, or Forms, be Perceived by the Senses? Hippias Major. Phaedo. Republic; 3. Why are Essences, or Forms, Unitary, Uniform and Non-Composite? Why are they Changeless? Eternal? Are they Logically Independent of Each Other? Phaedo and Republic; 4. The Relation between Knowledge and Enquiry in the Phaedo; 5. Why are Essences, or Forms, Distinct from Sense-Perceptible Things? Phaedo 74 and Republic V. 478–479; 6. Why are Essences, or Forms, the Basis of all Causation and Explanation? Phaedo 95–105; 7. What is the Role of Essences, or Forms, in Judgements about Sense-Perceptible and Physical Things? Republic VII. 523–525; 8. Why does Thinking of Things Require Essences, or Forms? Parmenides; 9. Why are Essences, or Forms, Separate from Physical Things? Also Timaeus and Philebus; 10. What Yokes Together Mind and World? Phaedo 99–100 and Republic VI. 505–509; Conclusion: Forms Simply are Essences, not Things that have Essences.

Vasilis Politis is Professor of Philosophy at Trinity College Dublin. He is author of numerous books, including The Structure of Enquiry in Plato's Early Dialogues (Cambridge, 2015) and The Aporetic Tradition in Ancient Philosophy (with George Karamanolis, Cambridge, 2018).

• Introduction; 1. Why Cannot the ti esti Question Be Answered by Example and Exemplar? Hippias Major; 2. Why Cannot Essences, or Forms, be Perceived by the Senses? Hippias Major. Phaedo. Republic; 3. Why are Essences, or Forms, Unitary, Uniform and Non-Composite? Why are they Changeless? Eternal? Are they Logically Independent of Each Other? Phaedo and Republic; 4. The Relation between Knowledge and Enquiry in the Phaedo; 5. Why are Essences, or Forms, Distinct from Sense-Perceptible Things? Phaedo 74 and Republic V. 478–479; 6. Why are Essences, or Forms, the Basis of all Causation and Explanation? Phaedo 95–105; 7. What is the Role of Essences, or Forms, in Judgements about Sense-Perceptible and Physical Things? Republic VII. 523–525; 8. Why does Thinking of Things Require Essences, or Forms? Parmenides; 9. Why are Essences, or Forms, Separate from Physical Things? Also Timaeus and Philebus; 10. What Yokes Together Mind and World? Phaedo 99–100 and Republic VI. 505–509; Conclusion: Forms Simply are Essences, not Things that have Essences.