What does "rather vaguely conceived sweetness and light" mean in this context?

Question

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.

• Sinclair Lewis, Main Street, Chapter 1

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. :)

Answer 1

Carol trusts in the fundamental goodness of the world, without quite knowing what it is ("vaguely conceived"), and this emboldens her to be more adventurous than the other girls.

"Sweetness and light" is an expression referring to the good and positive things in a culture. It came from Jonathan Swift's parable of the spider and the bee (bees make sweet honey and wax for candles). Matthew Arnold popularised it as a metaphor for what is important in a culture.