: "Of this Order the number is unknown; but of those that came to the North of Middle-Earth [ ... ] the chiefs were five."

: To my understanding this either means:

: a) that the only the masters of the Order came to ME while the majority of its members remained in Aman, or;
: b) that an unspecified number of Istari (one would suppose more than six) came to ME under that guidance of these five.

I'm not certain it means either, unless I've misunderstood you. The Istari by definition were sent to Middle Earth (cf. Unfinished Tales and the Appendix to LOTR). The total number of the Istari is unknown, where they went is unknown, but those who came to the Northern part of ME-with no suggestion of what relationship these five may or may not have had with the others, these five are the only ones Cirdan the Shipwright saw disembark-there are only 5. 3 you can name: Gandalf, Radagast, Saruman. The other two "blue" Istari Tolkien says passed into the East and their stories are "lost".
: Either way, 'therein lies a tale', so to speak.

: Any ideas?

: Cheers
: Berembrôg