In Jain metaphysics, there is a concept of six types of substances.[1] Among them dharma, adharma, space, soul and time- these five are massless substances.[2] They are called as agurulaghu. Agurulaghu substances are always massless. Pudgalāstikāya are both gurulaghu (with mass) and agurulaghu (massless).[3] In the case of matter, right from the atom up to the aggregate having four touches are agurulaghu. Kārmāṇavargaṇā (cluster of homogenous subtle particles of karma matter) is possessed of four kinds of touch. Hence, karmas are agurulaghu.[4] Among the five types of body, kārmaṇa body is agurulaghu and other four are gurulaghu.[5] Except kārmaṇa body, all the four bodies are made up of material aggregates with eight kinds of touches (Aṣṭasparśī). Mental and vocal activities are agurulaghu and physical activities are gurulaghu.[6] Here a question arises as to why are physical activities (kāyayoga) called absolutely gurulaghu? Since Kārmaṇa body possesses four touches and thus, its activity should have been agurulaghu.
Here, we cannot assume that kārmaṇa body possesses four touches but its activity (yoga) becomes aṣṭasparśī (possessor of eight touches) because mental and verbal activities are considered as agurulaghu. It seems that this statement is given for the four bodies except kārmaṇa body because kārmaṇayoga occurs only in antarāla gati (transmigratory state) and in kevalī samudghāta. So kāyayoga (physical activity) of only four kinds of body is prominently considered here. Considering the majority point of view, kāyayoga is called as gurulaghu. But in actuality, it seems to be a relative statement.