This is a quote from the book "The ​Virtue Of Selfishness" by Ayn Rand
...al material and of abstracting them into new concepts, of drawing inferences, of making deductions, of reaching conclusions, of asking new questions and discovering new answers and expanding one ’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.

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...
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