This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...s the feeling: “I am in control of my existence” — just as implicitly contained in the experience of pain is the feeling: “I am helpless.” As pleasure emotionally entails a sense of ef
ficacy, so pain emotionally entails a sense of impotence.
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Thus, in letting man experience, in his own person, the sense that life is a value and that he is a value, pleasure serves
as the emotional fuel of man’s existence.
Just as the pleasure-pain mechanism of man’s body works as a barometer of health or injury, so the pleasure-pain mechanism of his con...