quasi-reflex in character. The intellectual phase is abbreviated away. Habits are once voluntary and deliberated actions becoming mechanical in this way, and slipping out of the sphere of mind. For instance, many of the detailed movements of writing and walking are performed without any attention to the details. An excessive concentration of the attention upon one thing leads to absent-mindedness, and to its consequent absurdities of inappropriate, because imperfectly acquired, reflexes.
Text Book of Biology, Part 1: Vertebrata · The Wunder Library — complete classics, free to read, with narration.