Pearl is explicitly likened to the brook in this chapter:
Pearl resembled the brook, inasmuch as the current of her life gushed from a well-spring as mysterious, and had flowed through scenes shadowed as heavily with gloom.
In other words, because she is illegitimate and Hester will not reveal the name of her father, the source of her life is as much a mystery as the source of the flowing waters of the brook. She also is associated with the gloom of her mother's shame and her father's secret torments.
However, we are also told that Pearl is much happier than the gloomy brook, which is wreathed in shadows:
But, unlike the little stream, she danced and sparkled, and prattled airily along her course.
Like the forest, which is described as lovely and lush—Pearl and her mother sit, for example, "on a luxuriant heap of moss"—Pearl is a natural being, largely untouched by civilization. The narrator calls her an "elf-child," and Pearl abandons the sad babble of the brook as if she wishes to...
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