What does Chapter 38 teach about the prescribed spiritual duties for different cosmic ages (Yugas)?

Chapter 38 of the Sai Satcharitra references scriptural teachings about the primary spiritual duties prescribed for different cosmic ages, or Yugas. According to the text, the recommended path to spiritual progress has changed over time. Penance was the principal means in the Krita age (the first age), followed by Knowledge in the Treta age, and Sacrifice in the Dvapara age. For the current era, the Kali age, the chapter emphatically declares that Charity is the paramount practice. Specifically, it highlights food donation (Annadan) as the 'merit among merits' and the foremost among all deeds, which explains why Sai Baba himself regularly engaged in feeding people.