Among the non-living substances of the Jain universe, pudgala, matter, is the only one perceptible to the senses. Its very name is often analyzed as combining the ideas of combination and dissociation, for the essential behavior of matter is to aggregate and to break apart. Everything with form belongs to pudgala: earth, water, fire, air, bodies, sound, light, shadow, and the objects of all five senses. What defines matter is its possession of four fundamental qualities, touch, taste, smell, and color, together with the sensible dimension of tangibility. Wherever these are found, there is pudgala.
At the foundation of Jain material theory stands the paramanu, the ultimate atom. It is the smallest possible unit of matter, indivisible, without beginning or end, and so subtle that it occupies but a single point of space. The paramanu has no parts; it cannot be cut, burned, or grasped. Each atom possesses one taste, one smell, one color, and two of the qualities of touch. Yet atoms are not all identical, for they differ in the intensity of their qualities, and this variation, measured in degrees the texts describe with great precision, allows the same underlying atoms to constitute the endless variety of the material world.
Atoms rarely exist alone. Through the operation of their inherent qualities of cohesiveness, described as snigdha, oily or smooth, and ruksha, dry or rough, atoms combine to form aggregates called skandhas. When atoms of appropriate degrees of these qualities meet, they bind into molecules, and molecules combine into ever larger structures, building up from the imperceptibly fine to the grossly visible. All the tangible objects of experience are skandhas, temporary assemblages that will one day dissolve again into their constituent atoms. The atom is permanent; the aggregate is transient.
This atomism gives Jainism a remarkably physical understanding of many phenomena that other systems treat as immaterial. Sound, for the Jains, is not a quality of space but a form of matter, produced when material aggregates strike one another and propagate as subtle particles. Light and darkness, shade and heat, are likewise modifications of pudgala. Even the mind, in its physical substrate, and the breath that sustains life are understood as material. The body itself is a fine and ordered aggregation of atoms drawn together by the soul under the influence of its karma.
Nowhere is the significance of atomism greater than in the doctrine of karma. Jainism holds that karma is not a mere moral tendency but an actual subtle matter, karma-pudgala, composed of especially fine atoms that pervade the space occupied by the soul. When a jiva acts with passion, these karmic atoms are drawn to it and bind to the soul, a process called influx and bondage. They cling like dust to an oiled surface, obscuring the soul's innate knowledge until, ripening and yielding their effects, they at last fall away. Because karma is material, the discipline of asceticism can be understood as a real, almost physical, cleansing, wearing away accumulated matter through austerity.
The atom thus stands at the meeting point of physics and salvation. A paramanu is uncreated and indestructible, moving from one end of the cosmos to the other in a single instant, capable of infinite combinations, indifferent and inert. Yet upon the aggregation of such atoms into karmic bodies hangs the entire bondage of the soul, and upon their final dispersal depends its freedom. In the Jain vision the liberated soul is one from which every last atom of karmic matter has been shed, leaving consciousness alone, unclouded and complete, in a universe still teeming with the ceaseless dance of atoms.