This book has covered a wide range of topics, literally talking of shoes and ships and (sealing) wax, of cabbages and kings – as well as walruses and oysters, because fats come from such a variety of sources and contribute to so many different aspects of biology. All life needs lipids, and larger, more complex organisms like vertebrates have a special tissue devoted to their storage and management. Large body size and long life span would be impossible, except in an unnaturally constant environment, without the capacity for feasting during periods of plenty, and fasting when there is no time or opportunity for feeding.

The emphasis in protein and nucleic acid chemistry has long been on specificity: only one enzyme or receptor will do, and just one wrongly placed amino acid or base pair out of thousands is enough to spoil the whole molecule. Control and determinism is favoured over plasticity and adaptability: the very name ‘genetic engineering’ implies that the scientist is in charge, trying to control organisms’ careers through their genes. In contrast, the impression that emerges from the study of the biology of lipids and adipose tissue is of plasticity, variability and adaptability. If one kind of fatty acid is in short supply, then another might do instead, certainly as a fuel, and quite possibly as a component of a membrane. Even if it isn't perfect, it is a lot better than nothing, though small differences in its melting point or affinity for other lipids may affect where its owner can live and what it can do.

If lipid biochemistry strikes protein chemists as biologically amateurish, anatomists regard adipose tissue as beyond the pale.