Steinbeck goes light on the imagery in this dialogue-driven work, but he sure does bring down the hammer when he describes the lamp hanging in London's tent. This light weakly illuminates a sad scene: we've got Joy's coffin, a feverish Jim, and some pouring rain. The lamp decides to participate in the misery:
On the tent-pole the lamplight yellowed and dropped to the wick. A blue flame sputtered for a while, and then went out. (163)
We could talk about the symbolism of darkness and light, or about how the light of hope once kindled in the workers has given in to the darkness of oppression and poverty. Or maybe we could talk about how the flickering lamp is an acknowledgement of Joy's passing and a foreshadowing of the end for Jim. But we think Steinbeck pretty much hands you this one on a platter.