In science fiction and phantasy, authors often play with the idea of telekinesis, the ability of the mind to move objects at a distance. This reflects the idea that the mind is the most powerful part of the body. In one sense, this is true. In the long run intelligence always prevails over brute force. [...]
It has always been dangerous to work in mines. The roof may fall in and there are risks of flooding and explosion. Over the years, miners found that keeping canaries in the mines was a good early warning system. The birds were likely to die if there was a gas build up and this gave [...]

