Perhaps the most original contribution of Jain cosmology is its doctrine of two subtle substances, dharma and adharma, conceived not as moral principles but as physical media. In this technical usage the words carry none of their usual ethical meaning. Dharma here is dharmastikaya, the medium of motion, and adharma is adharmastikaya, the medium of rest. They are two of the five extended substances, and they exist for a single purpose each: to render movement and stillness possible for souls and matter.
Jain thinkers reasoned that motion cannot be explained by the moving thing alone. A fish swims of its own effort, yet it can swim only because water surrounds it and permits its passage. The water does not push the fish; it neither initiates nor compels the motion. It simply provides the neutral, passive condition without which motion could not occur. In just this way, dharma pervades the cosmos as an invisible, formless, all-penetrating medium that accompanies and enables the motion of every soul and every atom, without ever causing that motion or determining its direction. The impetus comes from the moving thing; the possibility comes from dharma.
Adharma is the exact counterpart. As the shade of a tree offers a traveler a place to halt without forcing him to stop, so adharma provides the condition that makes rest possible. It does not seize things and hold them still; it merely allows stillness where the moving thing chooses to cease. Motion and rest are thus not opposites produced by force and its absence, but two states each requiring its own enabling medium. Neither substance is ever active; both are auxiliary causes, present everywhere within the cosmos, silent and unfelt.
Because they are formless and without the qualities of matter, dharma and adharma cannot be seen, touched, tasted, or smelled. They possess no color and occupy no particular place, for each is a single indivisible substance that fills the entire cosmic region uniformly. They are known not by perception but by inference and by the authority of scripture, deduced from the very fact that motion and rest occur in an orderly, bounded universe.
Here lies the deepest cosmological consequence of the doctrine. Dharma and adharma are coextensive with one another and together define the lokakasha, the inhabited universe, the space in which anything can move or rest. Beyond this region stretches the infinite alokakasha, pure empty space, into which dharma and adharma do not extend. And because the media of motion and rest are absent there, nothing whatsoever can enter it. No soul, no atom, no aggregate can pass beyond the boundary of the cosmos, for without dharma there is no possibility of motion into the void. The shape and the very finitude of the inhabited world are thus fixed by the extent of these two substances.
This has a striking implication for liberation. When a soul attains moksha and sheds the last of its karmic matter, its natural tendency is to rise straight upward, for the freed soul moves spontaneously toward the summit of the universe. Yet it does not rise forever. It ascends only to the very edge of the lokakasha, to the topmost region called the Siddhashila, and there it halts eternally. It stops not because it is barred by any wall but because at that boundary the medium of motion comes to an end; beyond lies only the void where movement is impossible.
In dharma and adharma, then, Jainism finds an elegant and self-contained explanation for why the cosmos has the form it does, why it is finite yet uncreated, and why even the liberated soul comes to rest at its crown. Few systems have made two invisible, purely permissive substances bear so much cosmological weight.