Recent scholarship has recognized some thematic connections related to onto-cosmological issues between two late Platonic dialogues, such as Philebus and Timaeus, and has tried to explain them in different ways. The aim of this paper is to contribute to such a debate by analysing an ancient exegesis of Timaeus 35a1-b4, that of Plutarch of Chaeronea, which made use of the ontological sections of the Philebus in his treatise on the cosmogony of the Timaeus. More specifically, this analysis will show that (...) the notions of ‘limit’ and ‘unlimitedness’ played a decisive role in the shaping of the “essence” of the world-soul according to Plutarch. (shrink)