What are Good and Evil anyway? How do you know? How is this related to Blake's ideas of Reason/Energy?

William Blake was a poet who used to write poetry mostly romantic poems based on marriage, love, and attraction.

In one of his poem, 'The Marriage of Hell and Heaven' he stated that 'Attraction and Repulsion, Reason and Energy, Love and Hate are necessary to Human existence.' By this he meant that there can't just be one force working on this universe. If there's hate, there's also going to be hate.

He describe Good as Heaven and Evil as Hell. Heaven and hell is simply the acts of good doings and wrong doings.