Explain the probable allusion in the line "the minister and she would need the whole wide world to breathe in" from The Scarlet Letter.

This quote is from chapter 16, in which Hester is trying
to meet with Dimmesdale to warn him about Roger Chillingworth. The entire
quote:

But,
partly that she dreaded the secret or undisguised interference of old Roger
Chillingworth, and partly that her conscious heart imputed suspicion where none could
have been felt, and partly that both the minister and she would need the whole wide
world to breathe in, while they talked together,—for all these reasons, Hester never
thought of meeting him in any narrower privacy than beneath the open
sky.

The part to which you
refer means that Hester needs to meet with Dimmesdale outside, in the open sky, because
it is too risky for her to meet with him in his study. Nobody would have suspected their
relationship because he is a minister, and if she visited him in his study, people would
have just figured she was in need of counseling. Chillingworth, on the other hand,
suspected that Dimmesdale was the father of Hester’s child, Pearl, so Hester did not
want to risk anything by visiting Dimmesdale in his
study.

I think there is a deeper meaning to that sentence
as well. In the tight little world inhabited by Hester and Dimmesdale, that closed up
world of Puritan society, the judgmental nature of the people suffocated Hester and
Dimmesdale. They could never declare their love. They had committed adultery, had a
child, lied about it – all sorts of sinful behavior in Puritan society. They could never
be free as long as they lived amidst this environment. So, the only place they would be
able to breathe would be the whole wide world, meaning a larger environment, an
environment that was free. Someplace other than Massachusetts in 1640. I think the
allusion is to another place, the world outside of Puritan New
England.