âOn Dreamsâ is part of Aristotleâs Parva Naturalia, a collection of works on the phenomena of human life. In this treatise, he hypothesizes that we dream because our sensory organs continue to function while we sleep. He compares dreams to hallucinationsâerrors in our sense perception. Aristotleâs view of dreams influenced philosopher Thomas Hobbes and psychologist Sigmund Freud, and it continues to fascinate readers today.