What led to 🧙Radagast's sudden disappearance from the story?

[Sulimo]

What happened to Radagast? Did he fail? He just kinda dropped out of the story when his dwelling near Mirkwood was found abandoned.

 

[Mouth_Of_Sauron]

While Radagast didn't necessarily abandon his role as Istari, it's generally understood that the Brown Wizard did not "pass into darkness", as Saruman the White or Gandalf the Grey, but rather became one with Ea itself. Radagast's preoccupation with nature, his birds and animals, Ents and plantlife drew him almost within the earth itself to the point where he was indistinguishable from the very birds and trees he cared for. The wars of Men and Elves meant naught to Radagast the Brown and he diminished into the earth.

 

[Sulimo]

Hmm that's interesting. Where did you read that?

 

[Bard the Bowman]

I think it's safe to assume nothing concerning the fate of Radagast, except that he cared more about the birds and beasts and plants.

 

[Elthir]

According to the Annales Cambriae...

573 (...) Merlinus insanus effectus est.[SUP]† [/SUP]

;*)