Here's a breakdown of the symbolism:
* Schoolyard/Children: This symbolizes innocence and the carefree nature of childhood. The children "strive" in their play, which can be seen as a metaphor for the struggles of life, yet they do so with a youthful exuberance that is soon lost. The speaker passing by the schoolyard signifies her leaving behind the world of the living, where such innocence exists.
* Fields of Gazing Grain: The grain, particularly the phrase "Gazing Grain," suggests a sense of ripeness, abundance, and the inevitable cycle of life and death. The grain's "gazing" can be interpreted as a metaphorical witness to the passing of time. It represents the passing of life and the finality of death.
* Setting Sun: The setting sun is a traditional symbol of the end of life, the fading of light, and the transition into darkness. It represents the speaker's journey towards death, a journey symbolized by the carriage ride. The fading light also represents the fading of the speaker's physical life, a natural end that comes to all living things.
These images together paint a picture of the speaker's journey towards the unknown. They highlight the contrast between the vibrancy of life, embodied by the children at play and the ripening grain, and the inevitable darkness of death, represented by the setting sun. It's a journey of both sorrow and acceptance, a quiet acknowledgement of the natural cycle of life and death.
It's important to note that Dickinson's poetry often invites multiple interpretations. These are just some possible readings of the symbolism, and other readers may find additional meanings within the lines.