Cognition
Cognition is "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses processes such as attention, the formation of knowledge, memory and working memory, judgment and evaluation, reasoning and "computation", problem solving and decision making, comprehension and production of language. Cognitive processes use existing knowledge and generate new knowledge.
Perception
Perception (from the Latin perceptio) is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information, or the environment.
Action
When a man asks himself what is meant by action he proves that he isn't a man of action. Action is a lack of balance. In order to act you must be somewhat insane. A reasonably sensible man is satisfied with thinking.
Georges Clemenceau, Clemenceau, The Events of His Life as Told by Himself to His Former Secretary, Jean Martet (1930) as translated by Milton Waldman; Conversation with Jean Martet (1 January 1928), Chapter 12.