I love science, and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awed by nature. Science is not meant to cure us of mystery, but to reinvent and reinvigorate it.

If a rat is a good model for your emotional life, you're in big trouble.

If I had to define a major depression in a single sentence, I would describe it as a "genetic/neurochemical disorder requiring a strong environmental trigger whose characteristic manifestation is an inability to appreciate sunsets.

On an incredibly simplistic level, you can think of depression as occurring when your cortex thinks an abstract thought and manages to convince the rest of the brain that this is as real as a physical stressor.

Depression is not generalized pessimism, but pessimism specific to the effects of one's own skilled action.

Prior to the monotheistic Yahweh, the gods made sense, in that they had familiar, if supra-human appetites—they didn’t just want a lamb shank, they wanted the best lamb shank, wanted to seduce all the wood nymphs, and so on. But the early Jews invented a god with none of those desires, who was so utterly unfathomable, unknowable, as to be pants-wettingly terrifying. So even if His actions are mysterious, when He intervenes you at least get the stress-reducing advantages of attribution—it may not be clear what the deity is up to, but you at least know who is responsible for the locust swarm or the winning lottery ticket. There is Purpose lurking, as an antidote to the existential void.

Most people who do a lot of exercise, particularly in the form of competitive athletics, have unneurotic, extraverted, optimistic personalities to begin with. (Marathon runners are exceptions to this.)

The brain is heavily influenced by genes. But from birth through young adulthood, the part of the human brain that most defines us (frontal cortex) is less a product of the genes with which you started life than of what life has thrown at you. Because it is the least constrained by genes and most sculpted by experience. This must be so, to be the supremely complex social species that we are. Ironically, it seems that the genetic program of human brain development has evolved to, as much as possible, free the frontal cortext from genes.