A king may be a tool, a thing of straw; but if he serves to frighten our enemies, and secure our property, it is well enough; a scarecrow is a thing of straw, but it protects the corn.
The end and aim of spying in all its five varieties is knowledge of the enemy; and this knowledge can only be derived, in the first instance, from the converted spy. Hence it is essential that the converted spy be treated with the utmost liberality.