"This can be said to be good at selling casks, but not good at selling pearls" means that this can be said to be good at selling boxes, not good at selling pearls. From Han Feizi in the Warring States Period, "Han Feizi: On the Left of the Outer Reserve".
Original text:
Some Chu people sell their pearls in Zheng, which is a cabinet of magnolias, smoked with cinnamon pepper, decorated with pearl jade, decorated with roses, and compiled with jadeite. The people of Zheng bought the casks and returned the pearls. This can be said to be good at selling casks, but not good at selling pearls.
This story tells us that we should learn how to choose between the less important and the more important. We must distinguish between the primary and the secondary so as to complete things correctly. When doing things, we must be clear about the primary and secondary. We can't pay attention to the appearance of things and not see the essence of things like people who buy casks and return pearls. Only by seeing clearly the essence of things and distinguishing the primary and secondary, can we choose properly. The idiom originally refers to the return of pearls from a wooden box bought to hold pearls; It is used to mean that the minor things are better than the major ones when the choice is improper.
