 The hymns (Catuḥstava). There is some discussion which of the various hymns ascribed to Nāgārjuna actually make up the quartet of ‘four hymns’ often referred to in the commentarial literature. They differ in interesting respects from the works mentioned in the preceding section. Common to many of them is a positive conception of ultimate truth which ascribes specific qualities to it and gets close to the theory of Buddha-nature (tathāgatagarbha) that became very important in the later development of Buddhist thought.