From earliest times, in the production of evidence, courts have required to be produced the best evidence of which the case in its nature is susceptible, if obtainable. This is known as the "best evidence rule," and allows no evidence to be introduced which indicates that the party offering it can produce better evidence. It does not require the strongest possible evidence, or all the evidence of which the case is capable, but excludes only that evidence the nature of which indicates the existence of better and more original sources of information. For example, a title by deed must be proved by the production of the original instrument itself, if it is within the power of the party; its execution and delivery may then be proved by any one who witnessed the same.