Did Sai Baba's Guru give him a secret mantra, and what does this mean for Baba's own teachings?

No, Sai Baba explicitly states that his Guru did not give him a secret instruction or 'ear-mantra.' In a conversation recorded in Chapter 19, Baba recounts how he served his Guru for twelve years, yet his Guru never blew a mantra into his ears. The Guru's method of teaching was based on love, protection, and a nurturing gaze, not on verbal formulas. Because of this experience, Baba explains that he, in turn, does not give such mantras to his devotees. He uses the analogy of a mother tortoise who nurtures her young from across a river with her sight alone, implying his protection and guidance are conveyed through his grace and gaze, not a secret word.