Chapter 10 says Baba's movements were 'imperceptible'. What does this mean, and what divine powers (Siddhis) are mentioned in relation to this?

In the context of Chapter 10, the term 'imperceptible' refers to the fact that no one was ever able to see how Sai Baba got onto or down from the narrow wooden plank he slept on, which was suspended from the ceiling. This mysterious ability is attributed directly to his divine powers, or Siddhis. The text questions how such a flimsy plank tied with rags could even support his weight, concluding it was possible because "Great Siddhis (powers) residing within Him." The chapter specifically alludes to the siddhi of 'Anima,' which is the power to become minute. It suggests that Baba could easily move in the forms of flies, insects, or ants, making his actions undetectable to human eyes.