In "The Dark Prophecy," Rick Riordan includes a profound quote attributed to Marcus Aurelius that reflects on the nature of life and mortality. He advises to view life from a perspective of having already lived it, suggesting that one should focus on making the most of the time that remains. This encourages an appreciation for the present and the importance of living purposefully.

The second part of the quote emphasizes the concept that neglecting to pursue one's potential leads to a personal darkness. It serves as a reminder to embrace life fully and to convey one's inner light, suggesting that it's crucial to actively seek fulfillment and purpose rather than succumb to stagnation.