 The Nyāya-Vaiśeṣika philosophers clearly distinguish between pleasure (sukha) and pain (duḥkha) on the one hand and the experience of pleasure (sukha-pratyaya) and pain (duḥkha-pratyaya) on the other hand. Pain and pleasure are qualities of the soul but they need to be cognized by the self in order to be experienced. This means that cognition has a special status among the qualities of self: no other quality can be experienced without cognition.