Fern Hill sounds too good to be true. In fact it sounds downright Eden-like. And if you found yourself thinking that as you read, well, we're betting that's just what Dylan Thomas would have wanted. All the religious imagery and symbolism tells us that the youthful innocence Adam and Eve must have experienced in Eden is a lot like the carefree joy the speaker felt as a kid at Fern Hill. And unfortunately, neither Eden nor Fern Hill lasts forever.
Line 17-18: Here the speaker says the "sabbabth rang slowly / In the pebbles." It's a cool image because pebbles don't "ring," but it's sort of like they're miniature church bells in the "holy streams." The speaker is assigning a religious importance to the setting. He'll do that throughout the poem, giving us the impression that his youth and where he spent it share a sacred meaning to him. Sabbath is a day of rest, and, for Christians, a holy day for praising God. Although the speaker isn't directly praising God here, he is describing the landscape as if it's a holy place worthy of praise.
Line 30: The speaker says, "it was Adam and maiden." This reference to Adam and Eve suggests innocence, as if the speaker is frolicking in Eden. The speaker's descriptions of the landscape are intertwined with his feelings about being young, so when he says "it was Adam and maiden," we can hear him saying being young on the farm was like being in the garden of Eden. Except instead of the snake tempting him away, it's time that will yank him out of his childhood paradise.
Line 33: The speaker says, "so it must have been after the birth of the simple light." Although he doesn't reference anything from the Bible, like "let there be light," we know he's talking about creation and the beginning of time. Once again, the landscape has taken on a "holy" significance. He may feel like he's watching the dawn of creation, and for this speaker, that lines up perfectly for how felt when he was young.
Lines 44-45: Time is leading children out of "grace." Youth has been associated with innocence, and yet, it's time—not guilt or sin—that leads children out of youth. Whereas the speaker felt like he was in an Eden while he was young on the farm, he's beginning to realize that time has taken him away from there, and he can't return.
Line 46: Here, Thomas uses a metaphor to describe the days as "lamb white." This could be an allusion to Jesus as the "Lamb of God," but the speaker is talking about time and not necessarily anything that aligns with Jesus' life. He's definitely sticking with his theme of youth as an innocent, glorious time.