A Cambridge Professor once asked one of his friends to lend him a book which he wished to consult. The messenger returned with the following answer: 'I never allow my books to be taken out of my study, but if you like to come there you are welcome to read as long as you please.'

Some days after this, the friend applied to the Professor for the loan of his bellows. Remembering the refusal he had lately met with, he replied: 'I never allow my bellows to be taken out of my room, but if you choose to come there, you are welcome to blow with them as long as you like.'