From A Chinese Garden of Serenity (1959), by Hung Tzu-ch’eng, translated by Chao Tze-chiang:

The mind is like a bright pearl. If obstructed by material desires, it is like a pearl covered with mud and sand. But if clasped by passions, it is like a pearl adorned with silver and gold. Accordingly, a scholar is afraid not of an unclean malady, but of the difficult cure of a clean malady; and he fears not a barrier in events, but the difficult removal of a barrier in principles.