Can you explain the concept of saints incarnating by their own will and how this makes them immune to the conventional cycle of birth and death?

Chapter 43 elaborates on this profound concept by explaining that certain beings incarnate by their own will with the sole desire for the welfare of devotees. They are not bound by the normal rules of existence. The text describes them as those who 'place their feet on the head of Time' and do not care for the span of life. For such beings, birth and death are false imaginations. As Chapter 43 states, Sai Baba appeared in Shirdi due to the past merits of devotees and for their protection. His departure was a willed act of merging into the unmanifest through the fire of Yoga, not a submission to death.