“Doth the universe lie within the compass of yonder town, which only a little while ago was but a leaf-strewn desert, as lonely as this around us?”
Hester is trying to persuade Dimmesdale to leave their town and begin a new life with her. She points out that he is so attached to something that is only temporary and man-made, in contrast with the natural world all around them. By suggesting that the physical town is something artificial, Hester also implies that the rules and expectations of the community are arbitrary and simply made up by other human beings. They could choose to reject both, and live according to a new set of rules if they wanted to.
“See with what natural skill she has made those simple flowers adorn her! Had she gathered pearls, and diamonds and rubies, they could not have become her better.”
Hester is observing Pearl running around in the forest wearing flowers. Pearl is completely at home in a natural environment, whereas she has been rejected by a social one due to the stigma around her birth. By contrasting the flowers with precious jewels, Hester implies that people tend to value the wrong things. They focus on material wealth or social reputation, rather than embracing the purity of the natural world.
“I seem to have flung myself---sick, sin-stained, and sorrow-blackened—down upon these forest leaves and to have risen up all made anew.”
Dimmesdale says this line when he meets Hester in the woods. The experience of being in the natural world seems to have a healing effect on his sad mind and sickly body. What Dimmesdale doesn’t seem to realize is that this healing and liberating effect comes not just from the exposure to the leaves and trees, but also from the way in which the natural world is not ruled by social expectations. Dimmesdale’s obsessive guilt happens because he worries about social and religious rules, and when he enters a space where those rules do not matter, he immediately begins to feel better.