Knowledge is the basic attribute of a soul. To know the knowable is the attribute of knowledge. The soul knows the knowable objects not just by comprehension and knowledge but also by the functioning capacity of knowledge.
In Jainism, the cognitive function of a soul is translated as ‘Upayoga’. ‘Upa’ means to go near, and ‘yoga’ means the functioning of knowledge-perception. That means the functioning consciousness through which the soul gets oriented towards the act of knowing and perceiving is Upayoga. It is actually Upayoga through which the seeker realizes and differentiates the soul being independent from the body. That is why the Jain seers have said Upayoga as basic attribute of the soul.
Upayoga is of two types, Knowledge and Perception. Knowledge means by which the soul knows the special attributes of the subject. Perception means by which the soul knows the general attributes of the subject. The functioning consciousness with both knowledge and perception is known as ‘Gnanopyoga’ and ‘Darshanopayoga’ respectively. Here, Gnanopayoga can be translated as ‘the functioning consciousness as knowledge’ and Darshanopayoga can be translated as ‘the functioning consciousness as perception’. Knowledge, Perception, Power and Bliss are the four basic qualities of a soul. Despite infinite energy (power), without Upayoga the soul is unable to comprehend the object. Infinite energy here operates the knowing, perceiving capacity as well as bliss of the soul. That is why the functioning consciousness with knowledge and perception is termed as Upayoga.
Upayoga is ever functioning attribute of a soul. Not any soul is without Upayoga for even a moment. Upayoga is always functioning in every soul, although the subject changes with time. The change of subject is regarded as Emergence, Cessation and Permanence of Upayoga. That means when Upayoga is functioning on some particular object then it is called Emergence, when it changes and functions towards a new object then the previous object’s functioning is called Cessation. The continuity of Upayoga between the changes is called Permanence. The maximum time of functioning of Upayoga on any object is 48 minutes for any mundane soul. The alternate term of Upayoga is ‘Chitta’ or psyche.