This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
... cause to effect cannot be reversed. It is only by accepting “man’s life” as one’s primary and by pursuing the rational values it requires that one can achieve happiness — not by takin
g “happiness” as some undefined, irreducible primary and then attempting to live by its guid- ance. If you achieve that which is the good by a rational standard of value, it will necessarily
make you happy; but that which makes you happy, by some undefined emotional standard, is not necessarily the good. To take “whatever makes one happy” as a guide to action means: to be guide...
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