Introduction: One by Number. 1. Platonic Cosmology on Plotinian Terms. Ennead VI.6 and the Timaeus. Origin of Multiplicity in Plotinus. Plotinus' apostasies and Numenius' stasis. The Universe as Degrees of Separation from the One. 2. Multiplicity as Number. Surfacing from the Neopythagorean Underground. Outward and Inward Direction of Multiplicity in VI.6. Multiplicity as Effluence and Unity. 3. The Number of Infinity. Plato's Position. Aristotle's Criticism of Plato and the Platonists. Plotinus' Answer. 4. Number and Substance. Plotinus' Three Hypotheses about Number in the Intelligible Realm. Is Substantial Number Discrete and Incidental?. The Whole Number of Beings. The Substantial and Monadic Number. 5. Number and the Universe. Substantial Number and the One. Substantial Number and the Absolute Being. Substantial Number and Intellect. Substantial Number and Beings. Substantial Number and the Complete Living Being. Soul and Number. The Unfigured Figure of Soul's Dance. 6. Unity of Thought and Writing. Porphyry and the Enneads. Enneads VI.6. Six Along with the Nines. Conclusion: In Defense of Plato. Bibliography. Index of Names and Subjects. Index Locorum