How did Sai Baba's teachings and actions challenge the concepts of caste and ritual purity?

Sai Baba fundamentally challenged the prevailing notions of caste and ritual purity through his actions and egalitarian attitude. As Chapter 7 explains, for someone surrendered to God, caste 'did not matter even in the slightest degree.' This was evident as even the 'best of Brahmins' and Agnihotris (keepers of the sacred fire), who were typically strict about ritual purity, would abandon their pride and prostrate before him. The text further illustrates his detachment from purity rules by noting that his mind felt no disgust even if a dog were to put its mouth in the food being served. For Baba, who had no ego regarding the body, all were the same regardless of their birth or caste.