There was one question on your mind. One thing that simply could wait not one moment longer. Why?

"Pardon?"

Why all this? What did Celestia hope to accomplish with whatever spell she wove over her people?

She looked shamed a moment, ears falling. "Our past was... far from peaceful. Like your own, we had periods of intense violence and upheaval. While I was supporting it alone, I slowly guided my ponies towards peace and contentment, but even I cannot assure I would always be there." She sank to her belly slowly, her eyes level with yours. "I thought to my legacy. I wanted a people that would remain happy and harmonious even when I had gone and left them. I... wanted them to be happy. They would be such a beacon of hope that other races would seek to emulate them, or so I foolishly aspired." She dipped her head a little. "Bear no mistake, I do not think myself any less than a fool for what I have done, and arguably much worse. There is the simple matter that this must be fixed first, then I will surrender myself for judgment."

Just how long ago was this?

She lowered her horn, aiming it at you with its lethal tip all too close. "First, an understanding. We are speaking of things not meant to be shared. I am expressing faith in you. We have taken you from your home under some false pretenses. We have demanded a sacrifice, even if it is one you don't seem too opposed to. I am returning some small part of this. I think... together we may operate better than as two competing players on a board where failure results in the loss of an entire people. Do you understand this?"

You weren't completely sure that moment, but you weren't sure how many ponies would even believe you if you started badmouthing Celestia in the first place, so you gave a nod.

"Excellent. The spell was woven five hundred years in the past. I see the confusion on your face. I remind you that Applejack's generation was the last generation. This problem was unnoticeable at first. A minor nuisance barely worthy of note after that. A growing but small concern following that. Those who kept track of the numbers that pointed to it didn't even associate it with the spell. Why would they? It had nothing to do with fertility, or so they thought. So... I... thought. Every passing generation, my ponies grew less and less vital. Mares grew less able to make little ponies, and stallions less able to encourage the fact. It is only now, in our darkest hour, that we are truly in crisis." She shook her head. "I expect little more than scorn, and deserve worse, but let's save these ponies first. Save them, and then talk of punishments. The other way around will not serve them."

Author's Note

Mid-day update? You got it. This was, clear and ahead, the most popular question. Keep them coming! The interrogation is not yet over. Will she answer one more? 4? A dozen? Will she be cut off now? I ain't tellin', so get to asking.