The defining characteristic of dharmāstikāya is assistance in movement and of adharmāstikāya is assistance in repose.[1] Movement and repose-together modulates the system of the cosmos. Cosmic space is defined with the existence of medium of motion and medium of repose. Beyond that there is the existence of trans-cosmos. Thus, due to these two substances, the whole space gets divided into two divisions-cosmic space and trans-cosmic space.[2]
Coming, going, speech, climbing, mental, verbal and physical activities and other actions or movements occur with the assistance of dharmāstikāya.[3] Similarly, sitting, sleeping, standing, concentrating the mind and other such reposing or stable conditions become possible with the help of adharmāstikāya.[4] Dharma and adharma both are assistants (auxiliary cause) in movement and repose respectively of sentient beings and matter.
The structure of the cosmos also depends on these two substances. The structure of the cosmos is stated as ' supratiṣṭaka'' triśarāvasaṃpuṭākāra'[5], but in actuality this structure is of dharma and adharma. Depending on the structure of these substances, the structure of cosmos is explained. The dividing line between cosmos and the trans-cosmos is based on these two substances. Without them, the distinction between cosmos and trans-cosmos is not possible. lokālokavyavasthānyathānupapatteḥ.
They are essential factors for the movement and repose and also for the division of cosmic and trans-cosmic space. Movement and repose occur in the entire cosmos hence, we need such potential entities which remain unmoved themselves are all-pervasive and non-existents in the trans-cosmic area. This logical statement informs us about the defining characteristic of dharma and adharma.
In the context of dharma and adharma, some people argue that since both are invisible, on what basis can we prove their actual existence?[6] In response, these are incorporeal substances and thus it is true that they can never become subject of our senses.[7] However, they can be inferred through their specific functionality (upagraha) - upagrahānumeyatvāt. In the tīkā (commentary) of Bhagavatī, it is said that the invisible objects can be known through their functional aspects.[8] Functions such as assistance in movement and repose are phenomenon of our direct experience. Through these functional aspects we can infer their existence.