Antwerp, Netherlands, 1560 – Ludovico Guicciardini sets pen to paper and reflects on the rapid growth of his city in recent years. He finds much to be pleased with. The city is richer and more populous than ever before. Traders of all sorts are flocking to the expanding market at Antwerp.

Remember the toy of pegs & holes? The game was to tap round pegs; square pegs; and triangular pegs into their proper holes? It taught us all, early on, to think of disparate things as components of categories.