Briefly describe Freud's comparison of the mind to an iceberg

What will be an ideal response?

The tip of the iceberg is consciousness. The larger portion, below the water, is outside awareness. Part of the submerged portion that can be seen from the surface is the preconscious; however, the vast majority of it is the unconscious. Material can pass easily from the conscious to the preconscious and back again; material from both can slip into the unconscious. Truly unconscious material, however, cannot be brought voluntarily to awareness because of psychological forces that act to keep it hidden.