Law of Contagion

The Law of Contagion was a one of the best known Laws of Magic.

It stated that any two objects which had ever been in contact with each other had an affinity for each other which was directly proportional to the product of the degree of relevancy of the contact and the length of time they were in contact, and inversely proportional to the length of time since they ceased to be in contact.

For example, a bullet has a strong affinity to the gun that fired it.

It was sometimes used to connect door locks to one specific key, so that someone without the Talent could not open the door even if he had an exact duplicate of the key. (The Law of Relevance was, however, the more effective method for the task, as even a sorcerer could not duplicate the connection between the lock and key if it was used.)