Sigmund Freud pictured the mind as an iceberg. Only a thin tip pokes above the water into awareness. The huge rest of it stays hidden below. Under the waterline, the id, ego, and superego pull against one another. The ego protects itself with unconscious defense mechanisms. Explore the parts, learn the defenses, then test yourself.
Freud's model of the mind
The dashed line is the surface of awareness. Everything above it is conscious. Everything below it is hidden. The preconscious sits just under the surface. The unconscious fills the deep.