Disclaimer: I own nothing; for fun, not profit; etc.
Spoilers: Only through the original novel's last section, Murder and the Afterlife.
Notes:I have always wanted to explicate this idea further than Maguire took it; but once I started to try, I realized why he left it the way he did. This is my last and best attempt.
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"You were devoted to Glinda, you were," Nanny said once, casting her a reproving glance softened by something the Witch did not care to identify.
Her name should have been strange to her ears and out of place in this house, but no matter. Glinda has ever been a force not far from her mind, one that checks her rather than guides her, in all her innocent, meandering ways. By this point, she cannot say if this Glinda has been corrupted by age and memory, her mind incorrectly reconstructing time and space electron by electron; or if it is Glinda who has corrupted herself; or, most likely, some measure of both.
There is a mauntery outside the Emerald City that bears her name, the Witch would tell someone – but who, here, in this place, and in this time? For who would understand what she herself does not? Glinda has never been far from her mind, no, but there's little to say on a subject not conducive to words, and badly suited for conversation in the first place.
For, there had been a time when:
"Look Miss Elphie," she'd once been told, arm in arm and skirt to skirt with her roommate. She'd done as instructed. "Sit a moment, if you'll promise me you won't start one of your polemics against religion in whatever form, and watch how the colored light from all this stained glass shifts across the space over the next hour."
And so they had, sequestered away by their own choosing in a dusty corner of the grand old cathedral as the sun set through the stained glass in a terrible and silent cacophony of too-brilliant light and no shadow at all: a secondhand translation of the death of the day.
"It really was an amazing inference, you know," Glinda remarked after some time, "the realization of how the perception of something so stationary and constant can be so quickly and vastly changed by something so ephemeral."
"And one easily applied to faith," Elphaba had remarked in turn, and pulled out an orange from her pocket, beginning to peel it. "It's an interesting moment in the evolution of the anthropology of the soul. But is it the soul that's the constant and faith ever changes, casting the soul into a different light – so to speak – or vice versa?"
But Glinda had slapped her hands lightly, reprimandingly, and the orange fell half-peeled to the ground. "Perhaps neither," she replied, quickly pocketing it. "Perhaps it's not by faith that one is able to understand one's soul at all. Perhaps it's through another source entirely, and we have ascribed to this entity the title of deity. You would know more on the subject than me, I would imagine."
She'd not commented further.
"You were devoted to her," Nanny had said, "and everyone knew it." Well, true enough; she'd not denied it. Glinda represents more to her mind than she'll ever be able to put to words, and more than she dares to want to verbalize; and yet Nanny's words pull on her very truths until her mind aches and her chest throbs, swollen, from her heartbeat, so that after a time, she is numb to the feeling and sleepless because of it.
There had been a time.