This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...tee of remaining conscious at all. Man’s particular distinction from all other living species is the fact that his consciousness is volitional.
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Just as the automatic values direc
ting the functions of a plant’s body are sufficient for its survival, but are not sufficient for an animal’s — so the automatic values provided by the sensory-perceptual mechanism of its c
onsciousness are sufficient to guide an animal, but are not sufficient for man. Man’s actions and survival require the guidance of conceptual values derived from conceptual knowledge. But conc...