The next milestone in the history of Sanskrit is the Grammar of Panini, which describes in complete detail a form of the language younger than that of the Brahmanas, and based on the spoken usage of the educated Brahmans of the time.
Panini’s exact date is unknown, but the fourth century b.c. may be given as a rough estimate. His grammar quickly gained universal acceptance, and as a result the form of the Sanskrit language as described by him was fixed for all time.
The reason why Sanskrit as a language evolved no further after Panini was not only his authority, but also the fact that by this time the Aryan language had become divided into two, on the one hand Sanskrit, the language of learning, and in particular the language of the brahman caste and of its religion, and on the other hand Prakrit, the language of the masses.
These terms did not in fact come into use until some centuries later, but the dichotomy was already established by the time of Buddha and Mahavlra. From this time on normal linguistic evolution affected only the vernacular language, Prakrit or Middle Indo-Aryan; Sanskrit remained fixed in the final form given to it by Panini,” and continued to be used as the language of the educated classes, although, as time went on, the difference between and the ordinary spoken language increased.
Although the gap between Sanskrit and the ordinary spoken language grew progressively, this did not have an adverse effect on the use of Sanskrit, but rather its importance grew with time. For instance the language of administration in Mauryan times, as attested by the inscriptions of Asoka, was Prakrit, and this continued for some centuries; but gradually Prakrit was replaced by Sanskrit until finally Sanskrit was almost exclusively used for this purpose. A similar development took place among the Buddhists.
Originally, according to the directions of Buddha himself, their texts were composed in Middle Indo-Aryan, and the scriptures of the Theravada School are preserved in one form of this, namely Pali, but later, shortly after the Christian era, the northern Buddhists turned to Sanskrit.
The old scriptures were translated into Sanskrit, and new works were composed in that language. As an intermediate stage some schools developed a mixed or hybrid language which continued in use for some time.
The Jainas, though at a much later date, followed the example of the Buddhists, and also began to compose in Sanskrit instead of Prakrit. On the whole it can be said that during the last 600 years of pre- Muslim India Sanskrit was more extensively and exclusively used than at any time since the close of the Vedic period.