Final answer:
Whitman's poetry includes both natural and man-made/urban elements, highlighting his vision of unity and celebrating the diversity of human experience.
Step-by-step explanation:
Whitman's use of natural elements in his poetry can be seen in his vivid descriptions of landscapes, such as the grass, leaves, and birds in "Song of Myself." On the other hand, he also incorporates man-made or urban elements in his poetry, such as buildings, streets, and crowds in "Crossing Brooklyn Ferry." The use of natural elements creates a sense of connection to the natural world and emphasizes Whitman's vision of unity and transcendence. Meanwhile, the inclusion of man-made or urban elements reflects Whitman's celebration of modern life and the diversity of human experience.