It is an abstraction, yes, but not quite. On the one hand, it is an abstraction as it is a hand unattached to a body. On the other hand it has many fingers – producers and consumers, and therefore it resembles the human hand. A true abstraction would be the bodiless and fingerless hand. Even geniuses can hardly envisage such a hand. For example, Euclid could see how the invisible hand of prime numbers, with its countless fingers, is spinning the Machine of mathematics, but he was unable to imagine the number zero – the number of fingers of a fingerless hand.