What is the 'tortoise-vision' analogy that Baba uses, and what does it teach about the relationship between a Guru and a disciple?

In Chapter 19, Sai Baba uses a powerful analogy he calls 'tortoise-vision' or 'Kurma-drishti' to explain the Guru-disciple relationship. He describes a tortoise on one riverbank whose young are on the other. The mother tortoise nourishes her children simply with her gaze; she provides neither milk nor warmth directly. The young ones, in turn, do nothing but meditate on their mother, and her sight alone sustains them. Baba uses this metaphor to illustrate how a Guru's grace and attention can nourish a disciple from afar. The disciple's role is to constantly meditate on the Guru, and this focused devotion alone is sufficient spiritual nourishment, much like the mother tortoise's gaze is the only food her children need.