When his apprentice asked why, the carpenter explained that the tree was of such poor quality that if it was made into a boat it would sink, and if it was used for a column it would be eaten by worms. It was precisely because it was useless that it had lasted to such a great age.
弟子問其故，木匠解釋：這是一棵作舟則沈，為柱則蠹的不材之木，但正因為無所可用，才能成為長壽巨木。