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.
You may have enemies whom you hate, but not enemies whom you despise. You must be proud of your enemy: then the success of your enemy shall be your success too.
Liberal institutions straightway cease being liberal the moment they are soundly established: Once this is attained, no more grievous and more thorough enemies of freedom exist than liberal institutions.
The most common cause of low prices is pessimism - some times pervasive, some times specific to a company or industry. We want to do business in such an environment, not because we like pessimism but because we like the prices it produces. It's optimism that is the enemy of the rational buyer.