"The most tender, the most tragic of illusions is perhaps to believe that our actions can add or subtract from the total quantity of good and evil in the world," suggests that people often hold an illusory hope that their deeds significantly influence the overall moral balance of the world. This perspective highlights the humility needed to accept our limited power in shaping global morality and the importance of genuine intentions over perceived impact.

Durrell's quote in "Clea" emphasizes the idea that individual actions, while meaningful on a personal level, may not fundamentally alter the broader scope of good and evil. Recognizing this can foster humility and a nuanced understanding of our role in the greater moral universe, encouraging us to act with sincerity rather than with the expectation of changing the world's moral fabric.