Why is the earth-world considered more important than heaven in Sai's philosophy?

Chapter 37 argues that the earth-world is of profound importance, even more so than heaven or the world of Brahma. The text posits that sensual pleasure is the same everywhere, whether for Indra in a celestial garden or a donkey in a dung-heap. One eventually falls from heaven after their merit is exhausted. The earth-world, however, is unique because it is the place where one can practice the science of the oneness of Brahman and the Self, which is the direct means to ultimate liberation. Even a fleeting life on earth is precious, as one who offers every action to God can attain the permanent place of fearlessness, a state more profound than any temporary heaven.