Step 1: Reframing the self-criticism:
Hamel's speech is both an apology and a warning.
Final Answer:
He admitted his own carelessness as a teacher — postponing lessons for trivial reasons — and criticised parents who preferred immediate income from their children's labour over education. He held the whole community responsible, including himself, for neglecting their mother tongue, and warned that a people who cleave to their language hold 'the key to their prison,' now lost through years of indifference.