Jain Metaphysics and Science: 3.1.2.3 Four Types

From structural aspect, physical reality can be classified into four types.

9. Skandha (aggregate)
10. Skandha -desa (aggregate fraction)
11. Skandha- pradesa (aggregate unit)
12. Paramanu

These are the four basic structural modification of physical reality, out of which infinite modes are produced

1. Aggregate: An aggregate is formed by combination of paramanus. The smallest aggregate is produced by two paramanus and the largest is the material spread extending over the whole cosmos.
2. Aggregate fraction: An aggregate fraction is a part of the aggregate (mentally divided). This is an example of physical division. Chemically a substance may be compounded of two or more elements. In this case, each element is an aggregate fraction. It should be remembered that division is merely conceptual. When, on the other hand, an aggregate breaks up physically or chemically into fragments, each fragment becomes a whole aggregate and not aggregate - fraction.
3. Aggregate - unit. An aggregate- unit is an indivisible undetached part of aggregate. This is also merely conceptual.
4. Paramanu. The infinitesimally small, indivisible and free particle of matter is paramanu. This is described in detail below.

Out of the four, the aggregate (skandha) and paramanu are the main types. The aggregates and paramanus are produced in three ways - by division, by union or by both.  Division: The breaking apart of an aggregate by internal or external cause is called division.   Union: Combination of different substances and bonding between them is called union   Division - Union: Division - union means division and union taking place in the same process simultaneously. An aggregate break up and at the same times combines with another aggregate to produce a new aggregate giving a division - union.

The pudgala may be extensive (sapradesa) or non-extensive (apradesa). A pudgal occupying one pradesa is said to be non-extensive. For example, a paramanu is non-extensive. From the consideration of substance an aggregate is extensive. But from the consideration of space an aggregate may be extensive or non-extensive (since up to infinite number of paramanus can be accommodated in one pradesa).