Answer:
The section "Slave of the wheel of labor, what to him / Are Plato and the swing of Pleiades?" best supports the theme that endless labor keeps human beings from reaching their full potential because it shows that the speaker believes that people who are enslaved to their work cannot appreciate or enjoy the higher pursuits of life, such as philosophy and stargazing. The phrase "wheel of labor" suggests a repetitive, monotonous cycle of work that dominates the worker's life, leaving no room for personal growth or intellectual pursuits. The rhetorical question "what to him / Are Plato and the swing of Pleiades?" emphasizes this point by implying that someone who is stuck in this cycle of work would have no time or energy to contemplate the beauty and wonder of the natural world or engage in intellectual pursuits.