Socrates's Soul Is Immaterial

Socrates suggests that the soul is not just distinct from the body, but capable of surviving independently. He will show that it is indeed immaterial, invisible and all things we expect a platonic dualist to believe about the soul. So how should we prove this? To use a rather lame joke that plato himself seems to find amusing, you will all recollect that in the meno, socrates has argued that when we seem to be learning, we are actually recollecting things we knew before we were born.