This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...nor involuntary — nor infallible. Man has to initiate it, to sustain it and to bear responsibility for its results. He has to discover how to tell what is true or false and how to correct his
own errors; he has to discover how to validate his concepts, his conclusions, his knowledge; he has to discover the rules of thought, the laws of logic , to direct his thinking. Nature gives him
no automatic guarantee of the efficacy of his mental effort.
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Nothing is given to man on earth except a potential and the material on which to actualize it. The potential is a supe...