In the so-called “erotic dialogues”, especially the Symposium and the Phaedrus, Plato explained why erotic desire can play an epistemic function, establishing a strong connection between erotic desire and beauty, “the most clearly visible and the most loved” among the Ideas. Taking the erotic dialogues as a background, in this paper I elucidate Plato’s explanation in another context, the one of the Phaedo, for discussing the epistemic function of erotic desire in relation to the deficiency argument and the affinity argument. (...) My claim is that the erotic desire of the philosopher is activated by the recognition of traces of the Ideas as something that the material world lacks and that, nevertheless, his soul is familiar with. This desire for the Ideas triggers the process of recollection, and thus erotic desire acquires a decisive role in the acquisition of knowledge in the Phaedo. In the final section of the paper, I highlight the contemporary relevance of Plato’s epistemology of erotic desire. (shrink)