The deep secret of the brain is that not only the spinal cord but the entire central nervous system works this way: internally generated activity is modulated by sensory input. In this view, the difference between being awake and being asleep is merely that the data coming in from the eyes anchors the perception.

Keep in mind that every single generation before us has worked under the assumption that they possessed all the major tools for understanding the universe, and they were all wrong, without exception.

One of the most impressive features of brains - and especially human brains - is the flexibility to learn almost any kind of task that comes its way.

You gleefully say, "I just thought of something!", when in fact your brain performed an enormous amount of work before your moment of genius struck. When an idea is served up from behind the scenes, your neural circuitry has been working on it for hours or days or years, consolidating information and trying out new combinations. But you take credit without further wonderment at the vast, hidden machinery behind the scenes.

Scientists often talk of parsimony (as in "the simplest explanation is probably correct," also known as Occam's razor), but we should not get seduced by the apparent elegance of argument from parsimony; this line of reasoning has failed in the past at least as many times as it has succeeded.

Many people prefer a view of human nature that includes a true side and a false side - in other words, humans have a single genuine aim and the rest is decoration, evasion, or cover-up. That's intuitive, but it's incomplete. A study of the brain necessitates a more nuanced view of human nature.

There is a looming chasm between what your brain knows and what your mind is capable of accessing.