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“We pay a high price for this ingenious neural machinery, though, because the default mode network is responsible for mind-wandering. “Experience sampling”—which involves asking people about their mood and thoughts at random moments throughout the day—suggests that our minds wander from what we’re actually doing an amazing 30 percent to 50 percent of the time that we’re awake, and that this is often associated with feelings of unhappiness.6–8 According to Harvard psychologists Matthew Killingsworth and Daniel Gilbert, who created an iPhone app, Rate Your Happiness, to gather some of this data, fluctuations in happiness depend more on what we’re thinking than what we’re doing. Crucially, the results suggest that mind-wandering is the cause rather than the consequence of negative emotions. As the opening verse of the Dhammapada expresses it, “Our life is shaped by our mind; we become what we think. Suffering follows an evil thought as the wheels of a cart follow the oxen that draw it.”9 Less poetically, the psychologists concluded that “the ability to think about what is not happening is a cognitive achievement that comes at an emotional cost.” So, while”
― James Kingsland, Siddhartha's Brain: Unlocking the Ancient Science of Enlightenment