Why do the children use the flowers while flying?

Mrs.
Whatsit gives the children flowers for them to breathe through as they fly higher and higher
into the rarefiedof Uriel. The children fly over an Edenic garden in which beautiful creatures
dance to music; no wonder that Meg finds it so blissful.

Here, as elsewhere
in chapter 4, nature is presented as a source of joy and wonder, a much-needed antidote to the
infinite darkness of the Black Thing. That the children can breathe through the flowers
indicates that nature is a source of life, a precious gift given to us by the Almighty. Just as
flowers represent a thriving habitat for countless birds and insects, they also allow the
children to maintain a connection to the earth far beneath them while enjoying a God's-eye
perspective on things.