In all the aṅga āgamas from Ācārāṅga to Vipākasūtra, Aupapātika, Rājapraśnīya and all the upāṅga āgamas and Daśavaikālika, Uttarādhyayana etc. Mūla āgamas, Pṛthvīkāya, Apkāya etc. all the five one sensed beings have not been mentioned as sthāvarakāya at one place. In Sthānāṅga, Uttarādhyayana and Jīvājīvābhigama among the six categories of beings, three are called as sthāvara and the rest three as trasa. Up to the time of Tattvārtha sūtra and its auto-commentary, the same idea continued as popular belief.
Trasakāya has been mentioned in the context of ṣaḍjīvanikāya in Daśavaikālika. There trasakāya includes two-sensed beings, three-sensed beings, four-sensed beings, five-sensed beings- infernals, animals, humans and deities.[1] It indicates living beings exceptional to these, are sthāvara. Single sensed beings are not mentioned in this classification so they are sthāvara living beings. Pṛthvīkāya, apkāya tejaskāya, vāyukāya and vegetation bodies are single-sensed living beings.[2]Worldly living beings are categorized through the availability of the sense organs in Prajñāpanā. There is no division of living beings on the basis of sthāvarakāya and trasakāya. However, the living beings have been divided on the basis of trasa and sthāvara in Jīvājīvābhigama.
Trasa and Sthāvara in Agama Commentary Literature
It is known in relation of trasa and sthāvara that earth-bodied etc. five kinds of immobile living beings have not been mentioned under a single class of sthāvarakāya in Jain āgamic literature, but the commentary literature has mentioned them under sthāvarakāya. The commentator of Uttarādhyayana counts tejaskāya and vayukāya as sthāvara, whereas these have been mentioned as trasakāya in Uttarādhyayana. The commentator has divided the mobile beings in two types as labdhi trasa (deliberate and voluntary motion) and gati trasa (spontaneous and un-deliberate motion). From two to five-sensed mobile beings are labdhi trasa. The fire and air are gati trasa. Though, they have the rise of sthāvara body determining karmas, yet due to the capability of movement, these are called trasa.[3]
Gati and Labdhi Trasa
It seems that in the very beginning, the division between trasa and sthāvara might have been done on the basis of movement (mobility). That's why fire and air were called trasa but the movement of an ant and air are not equal. The movement of an ant is guided by its own wish. It moves for sustenance and for avoiding dangers whereas the fire and the air do not have self wished motivation, they move because of their inherent nature. How can developed and undeveloped be considered on the same level on the basis of movement? When this fact was noticed, the system of trasa and sthāvara was established keeping the basis of the karma principle. Inspite of their movement, they are called as sthāvara due to the rise of sthāvara body determining karmas and those beings whose trasa body determining karmas are in rise are known as trasa. When the fire and the air were called trasa in the āgamas, then the appropriateness of that statement was presented on the basis of labdhi trasa and gati trasa. For a reasonable explanation of the Agamic sentences it was necessary to make division of gati trasa and labdhi trasa. This division is for understanding of the common masses.
At present in the Śvetambara and the Digambara traditions, earth, water, air, fire and vegetation are considered as sthāvara beings and two, three, four and five sensed living beings are accepted unanimously as trasakāya.
It still needs investigation that in śvetāmbara tradition, has regarded earth etc. and all the five as the sthāvara for the first time. As per the commentary in both Sthānāṅga and Uttarādhyayana, these five classes of living beings together have been called as sthāvara.