Swamped

"He thought they were ethereal illusions. Manifestations of people's fears and whatnot, given physical form because there was a strong magical source flowing through the rains. When the rain stopped, the illusions went with it." She shakes her head. "Hmmph! Ridiculous if you know how mana flow works. He might as well have said they were ghosts. But I didn't have another explanation to offer until now."

That explanation immediately gives you another question.

"How, uh, how does mana flow work? I don't understand a lot about magic."

"Well, I'm not going to get into the full details, but the short version is, you can't really store mana in water. Oh, it goes in there easily enough, but it doesn't like to stay for very long. And since clouds are water and rain is water, you can't have magical rain unless someone is actively casting a spell as it's raining. And that's no easy task."

"That sounds like it would make it hard to make magic potions," you muse.

"Oh, for those you just enchant the bottle. Much easier. Anyhow, unless you've got anything else important to share, I need to get back to work. The sooner we get you out of here, the better it'll be for everyone."

While you can agree with that, you feel like there's a lot you still don't understand about what's going on here. But you don't even know where to begin on asking questions about it, whether to the old woman or to the others.