Please answer a question about the following article about Sanskrit:

Sanskrit linguist Madhav Deshpande says that when the term "Sanskrit" arose it was not thought of as a specific language set apart from other languages, but rather as a particularly refined or perfected manner of speaking. Knowledge of Sanskrit was a marker of social class and educational attainment in ancient India, and the language was taught mainly to members of the higher castes through the close analysis of Vyākaraṇins such as Pāṇini and Patanjali, who exhorted proper Sanskrit at all times, especially during ritual. Sanskrit, as the learned language of Ancient India, thus existed alongside the vernacular Prakrits, which were Middle Indo-Aryan languages. However, linguistic change led to an eventual loss of mutual intelligibility.

Of what was Sanskrit once thought to be a divider?
social class
The context mentions Sanskrit as a marker of social class and educational attainment in ancient India. It was taught to members of the higher castes through the close analysis of Vyākaraṇins such as Pāṇini, who exhorted proper Sanskrit at all times during ritual.
This indicates that speaking Hindi properly or incorrectly differentiated one person's social status from another. Thus, it could be inferred that "social class" is what separated different people based on their ability to speak a language correctly (Sanskrit)..