An eternal tension between light and darkness: just another way "Crossing Brooklyn Ferry" is like Star Wars. The poem's imagery actually seems go grow darker as it progresses, as if to mirror the setting of the sun. Although darkness corresponds to evil and doubt, Whitman accepts it as a necessary part of nature, and not as a power to be fought and defeated.
- Line 2: The speaker implies that the sun is setting rather than saying so directly. He notices the clouds in the west because they are lit up by the sun "half an hour high." The sun is half an hour away from setting.
- Line 17: He looks into the future and imagines future generations seeing the same sun "half an hour high."
- Line 30: The imagery of the flying sea-gulls is some of the most majestic in the poem. The play of light on the "glistening" birds could be a symbol of the soul, part of which is known to us but most of which remains unknown, "in strong shadow."
- Lines 32-34: These imagery of beams of light moving outward from the shadow of the speaker's head suggests a halo.
- Line 49-50: As with the earlier image of the sea-gulls, here a bright light shines out in mostly dark surroundings. The "red and yellow" fires of the foundry contrasts with the black smoke that moves over the houses and the streets.
- Lines 68-69: The "dark patches" of shadowy light symbolize evil thoughts, or at least doubtful ones.
- Line 130: The speaker returns to the image of the chimneys and the foundry near the end of the poem.