Doug Downs defines rhetoric as the operating system by which humans make meaning and interact through symbolic communication. He views rhetoric as encompassing all aspects of human interaction, including nonverbal cues and the interpretation of sensory information by the brain. Downs identifies several key elements of rhetoric, including motivation, ecology, knowledge making, and identification. He also discusses Aristotle's canons of rhetoric and concludes that rhetorical acts are situated, motivated, contingent, interactional, epistemic, and embodied.