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“The brain is the primary mover and shaper of the mind.
It’s so busy that, even though it’s only 2 percent of the body’s weight, it uses 20–25 percent of its oxygen and glucose.
Like a refrigerator, it’s always humming away, performing its functions; consequently, it uses about the same amount of energy whether you’re deep asleep or thinking hard.
The number of possible combinations of 100 billion neurons firing or not is approximately 10 to the millionth power, or 1 followed by a million zeros, in principle; this is the number of possible states of your brain.”