Abstract: The Cartesian explanation of sensation includes a speculative account of how external and internal phenomena transmit information to the brain by triggering flows of animal spirits from the pineal gland. The distinctive patterns in the flow of spirits are called ‘ideas’. There is no reason to think that ideas resemble the realities that cause them. All animals have sensations in this sense, and exhibit corresponding behaviour.

Keywords: animal sensation, animal spirits, clear and distinct ideas, ideas, information, internal and external, sensations,