Drawings made on asphalt roofing paper (tar paper) with metallic pigments. The smell of tar evokes for me the primeval ooze of the La Brea Tar Pits in my native Los Angeles, where animal remains are still excavated. This underground source of fossils, fuel and prehistory is analogous to the upwelling of images from the unconscious mind.

Visual and auditory hallucinations that occur during the period between sleeping and waking are known as the "hypnagogic state"; those that occur in the state between waking and sleeping are the "hypnopompic state".