- Origins and History:
The Istari are Maiar like Sauron himself. Heren Istarion (“Order of Wizards” in Quenya) was an Order created in Valinor by the Valar, when they were made aware of Sauron’s growing power in Middle-Earth. A council of the Valar was organised by Manwë and they decided to sent three emissaries to Middle-Earth, to help the free peoples fight against Sauron.
Curumo (Saruman) was chosen by Aulë and Alatar (one of the Blue Wizards) was chosen by Oromë. They both stepped forward willingly to the task. Olórin (Gandalf) was commanded by Manwë to go, even though he didn’t want to. Olórin made it clear that he feared Sauron. He thought he wasn’t powerful enough to challenge Sauron (which is a proof that Gandalf was a humble Maia, even then) but he didn’t disobey Manwë when he insisted that Olórin should be the third Istari. "But at that Varda looked up and said: ‘Not as the third; and Curumo remembered it.” So Saruman’s jealousy of Gandalf started even back then, when Varda more or less implied that Saruman might not be the chiefest and most powerful of the Istari as he would like to be.