those Jedi Knights who became extremely talented and powerful in the use of the Force were often trained to become Jedi Masters. The criteria were for becoming a Jedi Master were somewhat nebulous, and over time it became mainly an honorific to describe those Jedi Knights who taken on a Padawan learner. Sometimes, an individual who performed as an exemplar of the Jedi Order would also be given the title of Jedi Master. The position of Jedi Master was, however, actually bestowed upon an individual, but the Jedi Council made no formal declaration about the differentiating factors. The Jedi Masters' roles were varied, from teaching the young Jedi Knights in the use of The Force to acting as intermediaries for the Old Republic. During the early years of the Jedi Order, Jedi Masters often took more than one apprentice, spreading their knowledge whenever possible. This all changed after the Battle of Ruusan, when the Jedi Knights believed that they had become too scattered to control. Taking a cue from the Sith, the Jedi Council limited a Master to a single Padawan learner. This limitation was removed in the wake of the Battle of Endor, as Master Luke Skywalker was forced to train as many individuals as possible to rebuild the Jedi Order. The Jedi Masters were not exempt from Palpatine's Jedi purge, and the Jedi Master Yoda is the only known Master to survive. Yoda was able to pass on his vast knowledge of the Force to Luke Skywalker, who continued to train in the use of the Force after Yoda's death and become the newest Jedi Master. It is rumored that the best and truest Jedi Masters do not truly die, but move on to some mystical state of being. Their physical bodies cease to exist, but their living essence is absorbed by the Force. No explanation has ever been given for this occurance, but it has also been observed that certain Jedi Knights have also disappeared after dying.