Classical Indian grammatical works are written in sutras, terse fragments that often cannot be understood without a commentary. The compression looks perverse until the conditions of their use are considered.
The form assumes an oral setting
Sutras were composed to be memorised and carried in the mind, not consulted on a shelf. Every syllable removed is a syllable a student never has to store or repeat.
A grammar covering an entire language is a large body of rules. Reducing it to a few thousand compact statements makes complete memorisation possible for a dedicated student.
Brevity was so valued that grammarians reportedly celebrated saving even half a syllable. That priority only makes sense where the whole work lives inside human memory.
Technical vocabulary carries the load
Much of the compression comes from an invented shorthand. Short artificial terms stand in for large classes of sounds or grammatical situations that would otherwise need long descriptions.
Once a student has learned the shorthand, a rule of four or five words can specify a condition that plain language would take a paragraph to state.
The cost is that the text becomes closed to outsiders. Nothing can be read casually, and the vocabulary must be acquired in order before anything else makes sense.
Rules are ordered so context can be inherited
A sutra rarely restates its conditions. It borrows them from the rules that precede it, so a fragment inherits the setting established several statements earlier.
This continuation principle removes vast amounts of repetition. It also means the sequence is load-bearing, and a rule quoted out of order can be read to say something it does not say.
The arrangement builds from general statements towards specific exceptions. Later rules override earlier ones in defined ways, which lets the system handle irregularities without listing every form.
Commentary was part of the design
The compressed text was never meant to stand alone. It was transmitted alongside a teacher's explanation, and later alongside written commentaries that unpacked each fragment.
That division of labour is deliberate. The sutra holds the exact rule in a stable, memorisable form, while the explanation can be adapted to the student in front of the teacher.
Commentaries also record disagreement. Where a fragment admits more than one reading, the arguments are preserved, which gives later readers a view of how the tradition understood itself.
The method spread well beyond grammar
Philosophical, ritual, medical and legal traditions adopted the same form. A field would be condensed into aphorisms, then expanded again by generations of commentators.
The pattern gave those disciplines a stable core with a flexible surface. The aphorisms changed very little while the interpretation around them moved with the questions of each period.
Modern readers often encounter the commentary rather than the root text, which reverses the original relationship and makes the compressed layer look like an afterthought.