Do read about his reactions to the music-dramas of Wagner, and how he reached into the history of the Drama to enhance his musical proclivities. Also look into the founding of his Schola Cantorum, an institution which brought back a reexamination of pillars of musical antiquity, such as Gregorian chant and the giant Palestrina, and how to meld these ancient entities into the existing fabric of late nineteenth century French music. Incidentally, Schola Cantorum exists today.
One of the dramas which d'Indy inculcated to enhance a really interesting musical output was an epic poem which goes back to the Assyrians, or Babylonians, or Sumerians, some two or more thousand years B.C. - Istar, an ancient princess, ventures into the Underworld (some of us call it Hell) in order to free her lover from eternal captivity. In doing so, she would have to enter and pass Seven Gates, discarding one of her garments (seven in number, of course) as she passes through each gate. When she discards her final garment at the Seventh Gate, and stands naked, her lover is freed.
To me, d'Indy may very well have been in a whimsical mood when he thought of how to bring music to this ancient story. He composes the Istar Variations.
The music BEGINS with the final variation! The most wholly clothed - and as each variation is introduced, it has lost an article of its clothing - it is less florid and colored, until after the final (the FIRST!) variation is completed, the Theme finally is given us, and in unison. There it (she) stands, naked as a babe.
This piece must therefore be hailed as one in the form of Variations in Search of a Theme.
I can easily imagine witnessing the reactions of one Papa Haydn, the master of Theme and Variations; if he were brought back just to witness his favorite personal form and see it placed in reverse. I just have to feel that a guffaw would escape him; knowing of his sense of humor.
d'Indy - a fellow who marched to the beat of his own drum.
Incidentally, this fellow was exceedingly gifted as a composer - listen not only to Istar Variations, but a composition which was arguably his most popular; a lovely piece of music titled Symphony on a French Mountain Air.
Do search him out, and you may well have considered finding d'Indy's music and thinking more than worthwhile...