The philosophical concept of love, of eros, begins with Plato and continues through centuries of Platonic tradition. Plato dedicates two of his finest dialogues to love, the Symposium and the Phaedrus, but the motif of philosophical eros runs throughout his entire corpus.
Plato assigns an unprecedented role to love: eros, the strongest and most complex human desire, functions as an unexpected inner ally on our path to true philosophy. Erotic attraction begins as an unreasonable passion, yet entails the possibility of being transformed into a kind of divine madness that urges man to uniting with the Forms. For Plato there is something of philosophy in love, because just like philosophers are placed between wisdom and ignorance, so is love --by definition unsated-- a daemon vacillating between lack and fulfilment.
In the Symposium Plato sketches a ladder of erotic ascension that in succession covers the attraction to a beautiful body, the attraction to all beautiful bodies, the attraction to beautiful souls, the attraction to beautiful creations and lessons, and culminates in the revelation that the true motive behind love is its identification with the ideal Beautiful, with the Form of beauty.
In the later dialogue Phaedrus Plato seems to consider the possibility of an inner conflict between the noble goal and the weak flesh. Philosophical eros is presented as the exclusively spiritual attraction and contact, between people of different age, maturity and wisdom -- the Phaedrus must have been the origin of the current view on “Platonic love”.
Love is the favourite metaphor Plato uses for the exhibiting the nature of philosophy. If philosophy is the live process of learning, then erotic conversation is the human activity coming the closest to this ideal.