Insentient Real (Ajiva)
All the objects that are bereft of sentiency fall under the class of insentient reals. There are five insentient reals namely medium of motion (dharma), medium of rest (adharma), space (akasa), matter (pungala) and time (kala). Together with the soul, they make six substances. For the medium of motion & rest the Jaina thinkers use the terms dharma & adharma, which ordinarily mean auspicious karmas (punya) and inauspicious karmas (papa) respectively.
Medium of Motion (Dharma)
We observe physical objects and living beings move from one place to another. Though they are inherently capable of motion, they cannot move without some assisting cause. And this assisting cause is the medium of motion. E.g. a fish has inherent capacity to swim but cannot do so without the assistance of water.
Medium of Rest (Adharma)
A tired traveler has an inherent cause to stop his motion but he will not stop on the way, unless he finds a shade of a tree. Here the shade of the tree serves as an assisting cause for his stoppage of motion. So also, though physical objects and living beings have inherent capacity to stop their motion, they cannot stop their motion without some assisting cause. And this assisting cause is the medium of rest.
Souls and physical objects are the independent agents of motion as also of stoppage of motion. By their own nature they move or rest. But that they require the assistance of some other force or principle is accepted even by modern scientists. It is noteworthy that early Jaina thinkers have posited the mediums of motion – rest as two assisting causes of motion & rest respectively. According to Jaina thinkers, the medium of motion does not itself impart motion to the physical objects & souls or set them in motion. So also, the medium of rest does not itself urge them to stop motion and to rest. But they passively assist them when the latter themselves undertake motion or rest.
Space (Akasa)
For Jaina thinkers, space is an independent substance. It is infinite in extent. It is present in the universe but also far beyond it over the non-universe. Thus, no substance is so extensive as the space substance. As it is omnipresent it cannot move from one place to another. The function of space is to offer room to other substances. Thus, space is a universal container in which all other substances are contained.
That space, which is related to the universe, is called the universe-space (lokakasa) and that which is beyond it is called the space-beyond-universe (alokakasa). The medium of motion (dharma) and medium of rest (adharma) are present in all directions & that region which is covered by their presence is given the name universe – loka. And the region which falls outside this universe is given the name ‘region beyond universe’ or aloka. It is only with the assistance of these two substances that souls and material objects move from place to place & rest. As these two substances are absent in the region-beyond universe, there exists neither an atom nor soul therein. Then what is there in aloka. There is nothing in it. It is simply the form of pure space.
There is one more argument to prove the division loka & aloka. The Jaina scriptural principle is that the soul moves upward as soon as it becomes completely free from all karmic atoms. But what is the limit of upward motion? The answer to it cannot be found unless the division of space into the universe space and space beyond universe through the presence or absence of the medium of motion & rest is accepted. The acceptance of this division allows us to say that the medium of motion, the assisting cause of motion, is present in the upward direction up to the highest point of the universe, so the upward motion of the soul freed from material karmic atoms stops as soon as it reaches the highest upward limit of the universe and there it stays, beyond that the medium of motion being absent it cannot move further.
Matter (Pudgala)
All physical objects from an atom to the grossest object are given the technical name ‘pugnala’. This term is a compound formed from two verbal roots viz ‘pur’ and ‘gala’, the meaning of the former is to fill – to integrate and that of the latter is to decay – disintegrate. The process of integration & disintegration we experience in our bodies & physical objects are incessantly going on. Every moment some free atoms get integrated into an aggregate & same time some integrated atoms get disintegrated from it. An atom is the ultimate unit of matter (pudgala). The object that comes into being as a result of the combination of atoms is called an aggregate (skandha).
To have the physical qualities of touch, taste, smell, color is the nature of matter. This constitutes its corporeality (murtata). It means the state of assemblage of the four physical qualities. For it the term ‘rupi’ is also used meaning one have rupa (color). From this it becomes clear why all substances except matter are called arupi (devoid of color).
Touch is admitted to be of eight types i.e. hard, soft, heavy, light, cold, hot, unctuous and arid. Taste is of five types i.e. pungent, bitter, astringent, sour and sweet. Smell is of two types good and bad. Color is of five types i.e. black, red, yellow, green & white. Thus, the types of all the four physical qualities are twenty in all. But each physical quality has numerous divisions & sub-divisions when viewed from their different degrees of intensity. Sound, light, shadow, hot radiation and darkness are the forms of matter.
According to the Jaina thinkers, all atoms are qualitatively the same. There are no four classes of atoms. Atoms combine to form an aggregate when they manifest the required degrees of cohesiveness and aridness. Atomic combination is to two types – one giving rise to dimension and shape and the other not. The Jaina thinkers recognize the possibility of an aggregate occupying that much space which a free atom occupies.
Time (Kala)
Time is experienced by all. A new thing becomes old, an old one decays and a decayed one is at last destroyed. Time substance is posited to account for the incessant minute imperceptible changes as well as perceptible gross changes. Without it these changes would not take place as it is assisting cause. Friends to my mind life is all about time. Things happen when the time is right. What is right time is a function of our karmas and the laws of nature.
Space-Point (Pradesa)
A space point means the most subtle (i.e. indivisible ultimate) unit. Medium of motion – rest, space & matter are the four insentient substances and one sentient substance the soul is possessed of many space points. All understand that the ultimate indivisible units of physical objects like a pot are atoms. And these atoms are called space points so long as they are integrated into the whole (avayavi). But when they are disintegrated from it and are free, they are called atoms.
The space points of the above-mentioned four non-physical substances are of a special type. They are mutually absolutely inseparable and form a perfect unity. They are never disintegrated or separated from their substances as those of a physical object like a pot are. They are identical with their substance; they together form an impartite unity. These four substances under consideration, which have space points of this type, are eternal.
Substances of the Nature of a Collection of Space-points (Astikaya)
A soul, medium of motion and rest possesses innumerable space-points each. Space has infinite space-points. Space confined to the universe has innumerable space-points, while space, which there in the region beyond the universe has infinite space-points. Thus these five substances (medium of motion – rest, space, matter, time) are of the forms of a collection of space-points. Hence they are called Astikaya i.e. formed of two words ‘asti’ (space-point) and kaya (a collection). So Astikaya means ‘that which is of the nature of a collection of space points’.
Medium of motion – rest and space are having only one individual or instance, souls are infinite and matter is a substance having infinite instances in the form of atoms. Time is not of the nature of a collection of space-points. In its case space-point is but a moment. There is no possibility of two moments existing simultaneously and hence there is no possibility of a collection of moments. As time is but a moment, the term astikaya is not applicable to it.
In all, there are six substances recognized in Jaina philosophy – five extended plus one non-extended. For those who do not regards time as an independent substance, there are five substances only.