Here's the relevant passage:
> "This rude [crude, unrefined] mechanical [material, earthly] and earthly [physical] clay [body] takes the form of passion. [strong feelings]
> And, like the indigent [poor, lacking] caterpillar [a weak, humble creature], on [upon] the stale [old] and unprofitable [useless] dung [waste] of [from] our [human] flesh [bodies] feeds [sustains itself] on [upon] our [human] substance** [essence]. [being] "
Hamlet compares the human body to clay, dung, and caterpillar, all representing fragility, impermanence, and physical weakness. This image of decay and vulnerability sets the stage for his contemplation of suicide and the fear of what might come after death.