With his passion for collecting, Hartwig had formed a habit that is peculiar to those who suffer from ‘collectionitis’: the belief that he alone had the right to talk about a vase that he owned, even after he had parted with it.

In America alone, people spent $170 billion on “direct marketing”—junk mail of both the physical and electronic varieties—last year. Yet of those who received unsolicited adverts through the post, only 3% bought anything as a result. If the bumf arrived electronically, the take-up rate was 0.1%. And for online adverts the “conversion” into sales was a minuscule 0.01%.

Gaussian curvature is a prime example; although defined in terms of shape operators, it belongs to this intrinsic geometry, since it passes the test of isometric invariance.

in short space would be so augmented , as they would be able with little to inwall themselves strongly