This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...of survival is reason. Man cannot survive, as animals do, by the guidance of mere percepts. A sensation of hunger will tell him that he needs food (if he has learned to identify it as “hunger�
��), but it will not tell him how to obtain his food and it will not tell him what food is good for him or poisonous. He cannot provide for his simplest physical needs without a process of thoug
ht. He needs a process of thought to discover how to plant and grow his food or how to make weapons for hunting. His percepts might lead him to a cave, if one is available — but to build the s...
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