Sylvia's heart gave a wild beat; she knew that strange white bird, and had once stolen softly near where it stood in some bright green swamp grass. (1.23)
Although Sylvia seems to know all the animals that live around her home, the white heron is a particularly magical and awe-inspiring creature. It's no wonder the hunter hasn't been able to locate it—or that he so desperately wants to.
There was an open place where the sunshine always seemed strangely yellow and hot [...] and her grandmother had warned her that she might sink in the soft black mud underneath and never be heard of more. (1.23)
Although the story is told in a realistic fashion, any passages about the white heron are tinted with mystical imagery. This marsh—the home of the white heron—is no exception. Eventually, we'll get to see this awe-inspiring locale first-hand.
Half a mile from home, at the farther edge of the woods, where the land was highest, a great pine-tree stood, the last of its generation. (2.1)
This tree, located in the most magical part of the forest, is a relic from a past age. As we come to see, this makes it practically a ladder to the heavens.
Now she thought of the tree with new excitement, for why, if one climbed it at the break of day, could not one see all the world? (2.1)
While this can be seen as an example of Sylvia's childishness at work, it shows that this oak tree is different from all the others in the forest. It provides a vantage point unlike any she's ever climbed.
The tree seemed to lengthen itself out as she went up, and to reach farther and farther upwards. It was like a great main-mast to the voyaging earth. (2.6)
Now this is truly awesome: As Sylvia climbs higher and higher, she feels an intense connection with the forest and the earth itself. Suddenly, her curiosity changes into downright awe.
Sylvia's face was like a pale star, if one had seen it from the ground, when the last thorny bough was past. (2.7)
At this point, the tree isn't the only thing that's magical—Sylvia is, too. She has reached her goal and transcended into the heavens, like mythical heroes of ancient times.
Sylvia felt as if she too could go flying away among the clouds [...] Truly it was a vast and awesome world! (2.7)
Although we've already seen how at one Sylvia is with the forest, this passage takes this idea literally. Sylvia has never experienced a connection with nature as deep as this.
There [...] flew two hawks with slow-moving pinions. How low they looked in the air from that height when one had one seen them before far up, and dark against the blue sky. (2.7)
This seems more like a dream than reality—and that might be exactly the point. This whole experience is helping Sylvia remember why she was so awestruck by the natural world in the first place.
Where was the white heron's nest in the sea of green branches, and was this wonderful sight and pageant of the world the only reward for having climbed to such a giddy height? (2.8)
This "wonderful sight" would have been enough for Sylvia at one point, but the entrance of the young hunter changes all of that. The question now becomes whether the hunter is enough to make Sylvia forget about the amazing experience she just had.
She remembers how the white heron came flying through the golden air and how they watched the sea and the morning together, and Sylvia cannot speak (2.13)
Sylvia returns transformed. She is awed and humbled by the things she just witnessed and can no longer even consider betraying the white heron. In many ways, she has just had a religious experience—her god just happens to be nature.