Hello Stephanie, Taking as read that it's all a matter of opinion, I think your definition of Joni's 3 musical periods does hold water, except that I would definitely put Mingus in the middle period, of which it seems to be in some ways a culmination (not an entirely positive one): the jazz influences that had become more pronounced over the previous three were slap bang in the foreground; lyrically it was more elliptical than ever - contrast Wild Things Run Fast, where the lyrics, by Joni's standards, are much more straightforward; and, to these ears, Mingus is the farthest Joni ever got away from "easy listening", while WTRF is much closer to that rubric.
When it comes to quality, for me the middle period is streets ahead of the others, with the exception of Blue, the transitional work, which sees a great leap forward, from "good", "promising" and "loads of potential" to simply "great". From then she was unstoppable through the rest of that decade, after which [those of a nervous disposition please avert your eyes] her brilliant flame cooled appreciably. I will be absolutely delighted if she scales those artistic peaks again, and given that Dylan and Neil Young, whose "fall from grace" was for more precipitous, have pulled rabbits out of hats at a time when all but their biggest fans must have given hope, I wouldn't bet against it. My big reservation is about revisiting her old songs - as far as I'm concerned, the great creative renaissance ain't gonna come from that direction! Azeem in London NP: Nick Drake - Five Leaves Left - Ah, would that this fragile genius had lived long enough to have beginning, middle and end periods...
