The threedhra, which word from dhra, " maintaining," "preserving," is defined as the power maintaining wisdom or knowledge. Dhra are "spells chiefly for personal use" (Eliot), as compared with mantra, which are associated with religious services. The Tiantai School interprets the "threedhra" of the
Lotus Sutraon the lines of the三谛, i.e. 空, 假and中. Another group is闻持陀罗尼 the power to retain all the teaching one hears; 分别陀罗尼 unerring powers of discrimination; 入音声陀罗尼 power to rise superior to external praise or blame.
