CC Ādi 16.31
bālya-śāstre loke tomāra kahe guṇa-grāma
Formerly Sanskrit schools first taught grammar very thoroughly, and this system continues even now. A student was supposed to study grammar carefully for twelve years in the beginning of his life, because if one is expert in the grammar of the Sanskrit language, all the śāstras are open to him. Śrī Caitanya Mahāprabhu was famous for teaching grammar to students, and therefore Keśava Kāśmīrī first referred to His position as a teacher of grammar. Keśava Kāśmīrī was very proud of his literary career; he was far above the first lessons of grammar, and so he thought the position of Nimāi Paṇḍita not at all comparable to his own.