How did Sai Baba teach a female devotee about the nature of true service?

In an insightful exchange recorded in Chapter 9, Sai Baba teaches a lady about true service and his own nature. When he tells her she has satisfied him, she is confused, stating she is dependent on others for her own food. Baba then explains that he had become completely satisfied by the 'bread of love' she had offered. He reveals that the hungry dog she had suddenly seen and fed was a form of himself. He states, "I have oneness with him," and extends this to other creatures like a pig. This lesson, that serving any hungry being is serving him, overwhelmed the lady with emotion and understanding.