This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...’s knowledge into an ever-growing sum. The faculty that directs this process, the faculty that works by means of concepts, is: reason. The process is thinking.
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Reason is the facu
lty that identifies and integrates the material provided by man’s senses. It is a faculty that man has to exercise by choice. Thinking is not an automatic function. In any hour and issue of hi
s life, man is free to think or to evade that effort. Thinking requires a state of full, focused awareness. The act of focusing one’s consciousness is volitional. Man can focus his mind to a f...