There are two important concepts in Jaina Metaphysics which are perplexing to students of Jainism, the astikayas and the dravya. The term astikaya is a compund name made up of asti and kaya which respectively mean existing and extensive magnitude. The other term dravya means the real that is fluent or changing. We shall try to explain these two concepts in detail.
The astikaya are five in number, jiva (soul), pudgala (matter), dharma (principle of motion), adharma (principle of rest) and akasa (space). These five build up the Cosmos. Space and matter are distinctly extended reals. Dharma and adharma are indirectly related to space. Their operation is in space and is limited by lokakasa. Thus they may also be considered as related to space. Lastly, Life is generally associated with body, the organic body constituted by pudgala or matter. Jiva is operative in and conditioned by such a physical medium. In a way therefore Jiva also is related to space. These five existences which have spaciality either directly or indirectly are the five astikayas. These are the consitituent elements of the universe or the world.
Kala or time though not an element of the physical universe may be mentioned here. Since change and motion are admitted to be real, time also must be considered real. The real or absolute time as contrasted with the relative time is constituted by simple elements known as kãlanus or instants. Instants, points and atoms are the characteristic conceptions of Jaina thought and in this respect it has a wonderful corroboration from the field of modern mathematics.
The Jaina thikers in distinguishing time from the five astikayas made use of an important idea. Astikaya is spatiality or extensive magnitude. This extensive magnitude is denoted by a technical name, tiryak pracaya or horizontal extension. When the simple elements, say, the points are so arranged in a series where each term is an item also in another series , we must have the two dimensional series which will correspond to surface or extension. Wherever there is such a tiryak-pracaya we have astikaya. But time or kala has only urdhava pracaya. The elements are in a forward direction. The series is mon dimensional or linear order. Therefore kala has no extension either directly or indirectly. Hence it is not an astikaya. Thought it is not astikaya it is distinctly a real entity which accounts for changes in other things.
Such are the characteristics of real time. This should not be confounded with vyavahara kala or relative time which is measured by some conventional units of either long or short duration. These conventional distinctions would have no meaning if they are not coordinated in a single real time series.
The term Dravya denotes any existence which has the important characteristic of persistence through change. Jaina conception of reality excludes both a permanent and unchanging real of the Permenidion type and also the mere external flux of Haraclites. An unchanging permanent and mere change without substratum are unreal, or impossible abstractions. Jaina system admits only the dynamic reality of dravya. Dravya then is that which has a permanent substantiality which manifests through change of appearing and disappearing. Utpada - origin, vyaya - decay and dhrauvya - permanency form the triple nature of the Real. To emphasise the underlying identity alone would end Vedantic conception of this Real as Brahman. To emphasise the change alone would result in the Ksanika vada of the Buddhist, the reality as a stream of discrete and momentary elements. The concept of dravya reconciles both these aspects and combines them into an organic unity. It is an identity expressing through difference, a permanency continuing through change. It corresponds to the modern conception of organic development rather in its hegelian aspect. It has duration; it is movement; it is the Elan Vital. The five astikayas and kala or time are the six dravyas or the real existences.