So here’s the thing. Your mind is not your brain. In fact, your brain is not your brain, or at least it’s only part of it. Tucked under the cortex we think we think with, are all the old brains, the hind-brains, the core structures of living and emoting and paying attention — and breathing.

Optimism is an emotion about the future, quite different from thankfulness, which bows to the past and acknowledges the present. That optimism is a feeling-for-no-reason gives us a clue that this emotion, like courage and love, is to be found in that mysterious region we call the heart.