When a friend, then, indulges in the joy of unburdening a secret on to another friend's bosom, he makes the latter, in his turn, feel the urge to taste the same joy himself. He implores him, it is true, not to tell a soul; but if such a condition were taken absolutely literally, it would at once cut off the flow of these joys at their very source. The general practice is for the secret to be confided only to an equally trustworthy friend, the same conditions being imposed on him. And so from trustworthy friend to trustworthy friend the secret goes moving on round that immense chain, until finally it reaches the ears of just the very person or persons whom the first talker had expressly intended it never should reach.
~ Alessandro Manzoni - [Secrets]