In "Come Up from the Fields Father," Walt Whitman uses imagery to evoke a shift in mood from the beginning to the end of the poem. At the start, the poem depicts a scene of idyllic autumn in Ohio, where the trees are deep green, apples are ripe, and grapes hang on the trellises. The sky is calm and transparent, and the farm is prospering well. The mood is peaceful and serene, and the imagery of nature is soothing and calming. However, the mood abruptly shifts as the mother receives a letter about her son, Pete, who has been wounded in a cavalry skirmish and taken to the hospital. The mother is stricken with grief, and the imagery turns dark and ominous. The mother's steps tremble as she rushes to open the letter, and the sentences are broken, with the main words flashing before her eyes. The image of the sickly white and faint figure leaning against the jamb of the door is striking and poignant. The mood then shifts to one of profound sadness and mourning as the family realizes that Pete has died, and the mother is left longing to be with her dear dead son. The imagery of the mother's thin form dressed in black and her fitful sleeping, weeping, and longing in the midnight hours evokes a sense of deep sorrow and loss. Whitman's use of vivid and powerful imagery effectively captures the changing moods of the poem, from peaceful and idyllic to dark and tragic.