This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...nism itself and directed to a single goal: the maintenance of the organism’s life.
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An organism’s life depends on two factors: the material or fuel which it needs from the outsi
de, from its physical background, and the action of its own body, the action of using that fuel properly. What standard determines what is proper in this context? The standard is the organism’
s life, or: that which is required for the organism’s survival.
No choice is open to an organism in this issue: that which is required for its survival is determined by its natur...