I would like to know what "rather vaguely conceived sweetness and light" means in the following sentences:
The other girls in her dormitory marveled at the slightness of her body when they saw her in sheer negligee, or darting out wet from a shower-bath. She seemed then but half as large as they had supposed; a fragile child who must be cloaked with understanding kindness. “Psychic,” the girls whispered, and “spiritual.” Yet so radioactive were her nerves, so adventurous her trust in rather vaguely conceived sweetness and light, that she was more energetic than any of the hulking young women who, with calves bulging in heavy-ribbed woolen stockings beneath decorous blue serge bloomers, thuddingly galloped across the floor of the “gym” in practise for the Blodgett Ladies' Basket-Ball Team.
Carol, a student at Blodgett College, had a very slight and thin body. So her friends regarded her as a fragile child, but she was more adventurous than any active young women in her college.
In this part, I could not understand what "rather vaguely conceived" means in particular. Does it mean that "sweetness and light" was vaguely expressed? And what is "sweetness and light" that was vaguely conceived?
I would very much appreciate your help. :)