Why did Sai Baba appear in Shirdi in the first place, and why did he eventually leave his body if he's eternal?

The text explains that Sai Baba's manifestation had a specific purpose. As detailed in Chapter 43, he appeared in Shirdi 'for the sake of the devotees’ protection,' drawn by their collective past merits and devotion. His incarnation was driven by the 'sole desire for the welfare of devotees.' His departure was not a passive event but a conscious decision. The scriptures suggest that once 'the task for the devotees was over,' he chose to leave his physical form. This was not a death but a willful act of a Yogi who could 'die at will,' allowing him to merge back into his 'previous unmanifest state' while continuing to guide devotees from within their hearts.