This is a quote from the book "The ​Virtue Of Selfishness" by Ayn Rand
...at man must live for his own sake, neither sacrificing himself to others nor sacrificing others to himself. To live for his own sake means that the achievement of his own happiness is man ’s h ighest moral purpose.

In psychological terms, the issue of man’s survival does not confront his consciousness as an issue of “life or death,” but as an issue of “happiness
or suffering.” Happiness is the successful state of life, suffering is the warning signal of failure, of death. Just as the pleasure-pain mechanism of man’s body is an automatic indicator of...
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