Shrink yourself down to the size of a molecule in the Krebs cycle. Succinate. The cell you’re part of is the size of a city, a metropolis on the scale of London, Tokyo or New York. What connects you with another molecule of succinate across the city, twenty miles away? In what sense are you part of the same entity, the same self? You won’t even be succinate for long. In a tiny fraction of a second, you will transform into malate, then oxaloacetate, or perhaps an amino acid or sugar. You are a fleeting moment in the kaleidoscope of metabolism, shape-changing a billion times a second. There’s no
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