“Conception” has to do with the creation of Gatsbyhimself; Gatsby is a self-made man financially. The key point is his love for Daisyand the reminiscence of their little love episode. “Platonic” comes from itsnoun form Platonism which means ‘the philosophy of Plato stressing especiallythat actual things are copies of transcendent ideas and these ideas are theobjects of true knowledge apprehended by reminiscence’ (Merriam Webster). Plato believed the world that we live in was anillusion of an idea or object that is beyond what we humans can comprehend.
Gatsby’s identity was created from his platonic view of himself: his view that hislove for Daisy was transcendent, it was beyond the normal, and it trumped theusual human limits. He made himself, his reputation and image to win Daisy’sheart back, believing their love was something pure and special. However, hewas wrong about Daisy’s love for him, which tying back into the beginning ofthe novel, she was the “foul dust” at the death of his dream.