Why do great souls like Sai Baba take on a physical body if they are beyond birth and death to begin with?

Chapter 43 explains that saints take on a physical form for a specific and selfless reason: the welfare of their devotees. Their incarnation is described as an act of grace, appearing for the sake of helping and protecting others. The text states they have a "sole desire for the welfare of devotees" and appear in a manifest form, gathered by the past merits of their followers. The physical body is merely a temporary vehicle, and to say Baba was limited to his three-and-a-half-cubit body is considered improper. Once their task is complete, they merge back into their true, unmanifest form.