Before the Two sisters became the sole guardians of the sun and moon, the Unicorns did their duty as Sun Seers and Moon Guides, raising and lowering the sun and moon over Equestria under the watchful eye of Starswirl the Bearded. However, each Seer and Guide would eventually deplete their store of magic, and would forever become magicless, with no way to recuperate.

It was an honour to be a Seer or Guide. It was a secret, shameful curse withheld from the other ponies.

Written as part of a prompt from my Facebook Group's head admin to write about a Summer Sun Celebration prior to Celestia and Luna taking up the Celestial Ceremony duties: https://www.facebook.com/groups/MLPAdmins/