Dewey, J. (1922). Section I: Habits as social functions. In J. Dewey, Human nature and conduct: An introduction to social psychology (pp. 14-23). NY, US: Henry Holt and Company.
http://dx.doi.org/10.1037/14663-001
Habits may be profitably compared to physiological functions, like breathing, digesting. The latter are, to be sure, involuntary, while habits are acquired. But important as is this difference for many purposes it should not conceal the fact that habits are like functions in many respects, and especially in requiring the cooperation of organism and environment. Breathing is an affair of the air as truly as of the lungs; digesting an affair of food as truly as of tissues of stomach. Seeing Involves light just as certainly as it does the eye and optic nerve. Walking implicates the ground as well as the legs; speech demands physical air and human companionship and audience as well as vocal organs. We may shift from the biological to the mathematical use of the word function, and say that natural operations like breathing and digesting, acquired ones like speech and honesty, are functions of the surroundings as truly as of a person. (PsycINFO Database Record (c) 2016 APA, all rights reserved)