In the most carefully calculated grand design is the one irrepressible element that throws everything out of whack. They are what we build our stories upon: that infinitesimal chance that the lid will gleefully flip on the most improbable of chaos.

When it happens on a stamp, there is that chance that a small fortune can be made.

One in a million? Look again.

Spot the blunder! This is a 1956 stamp from the former East Germany. The one on the left shows the portrait of composer Robert Schumann with music by Franz Schubert!

How stamps are made is hardly a matter of running off a few hundred sheets at the printer's. The long, fastidious process lends itself to a delicious hunt for rare human errors and mechanistic failures. An astute enthusiast delights in finding disparities - the ostentatious distinctions, subtle deviations and not forgetting those silly accidents. They delight in them not just for their economic value but the very stories that they inspire, waiting to be told.