The selective nature of perception is noted, we only notice some things. The automatic monitoring of perception by belief is noted, and the possibility of mistaken judgements of perception. How sensory stimuli are picked up by sensory organs and transferred to the brain as trains of action potentials is understood, but how the brain transcodes these similar trains to the different perceptions of sight, sound, smell, taste, touch, and pain is unknown. There are mysterious elements in how perceptions are projected from the brain to surrounding space and to other parts of the body. This projection may be a factor in the intuition of dualism. The ineffable nature of perceptions is demonstrated. The chapter ends with a note on the nature of mental imagery and its role in thought.