This tension, between the force of the material world and the will of the imagination, lies at the centre of this book.

ECONOMIST: When hocus-pocus is all but child's play

This peculiar tension, immovable object and irresistible force, is unlikely to change before election day.

ECONOMIST: Trick or treat?

To snap a typical paper-clip in tension by clamping one end and tugging on the other would require a force of 50lbs or so.

ECONOMIST: Aircraft fatigue