In Victor Hugo's "Les Miserables," the author describes certain individuals who metaphorically resemble crabs, moving sideways into darkness rather than progressing forward in life. These souls, instead of using their life experiences to grow and improve, tend to regress, compounding their flaws and moral shortcomings. This behavior results in a continuous decline into deeper levels of wickedness, where their negative traits become increasingly pronounced.

Hugo highlights the tragic nature of such individuals, as they squander opportunities for personal growth and healing. Instead of evolving and striving for redemption, they allow their past experiences to fuel their descent into a more corrupt existence. This commentary on human nature serves as a powerful reminder of the consequences of failing to learn from one's experiences and instead succumbing to a life of moral decay.