Throwback Thursday Tolkien style!
Finally, here's my versions of Gandalf, Saruman, and Radagast in their 'younger/original' Maiar forms as Olorin, Curumo, and Aiwendil.
'...Olórin I was in my youth in the West that is forgotten.' - Gandalf the Grey
Manwë summoned the Valar for a council at which it was resolved to send out three emissaries to Middle-Earth and he asked who would go. They would have to loose might and clothe themselves in flesh to win the trust of Elves and Men but this would also imperil them, diminish there wisdom and knowledge and bring upon them fear, the care and weariness of the flesh. Only two came forward; Curumo (Saruman) and Alatar. Curumo was chosen by Aulë among "his" Maiar and Alatar was send by Oromë. Manwë asked where Olórin (Gandalf) was and Olórin just returned from a journey and coming to the meeting asked what he wanted from him and Manwë told that he wished him to go as the third to Middle-Earth. Olórin answered that he meant himself to weak for such a task and that he feared Sauron. Then Manwë said that that was all the more reason why he should go and he commanded him to go as the third. There Varda broke in and said "Not as the third." and Curumo remembered that.
The narrative goes on to tell how Curumo (Saruman) takes Aiwendil (Radagast) at the pleading of Yavanna, and that Pallando is brought by Alatar as a friend (the Blue Wizards). With Olórin (Gandalf) added to the mix, the total of five Istari mentioned in the appendix to the Lord of the Rings is reached.
Five Maiar were ultimately chosen and they each came over the Sea appearing as mortals well into the later years of their existence. They were hearty beings but still subject to the weaknesses of the physical form. They felt hunger and weariness but they did not age. Nor were they vulnerable to sickness or natural deaths, though their physical bodies could be slain. The Istari were forbidden to reveal their true natures and display any supernatural powers so as not to intimidate the peoples of Middle-Earth.