What did Sai Baba mean when he told a lady she had fed him, even though she had only given food to a dog and a pig?

In a profound teaching on oneness described in Chapter 9, Sai Baba explained his identity with all living beings. A lady in Shirdi had given a piece of bread to a hungry dog and then saw a hungry pig. Later, Baba told her, 'Mother, you fed me today; by that, my stomach is full to the throat.' When she was confused, Baba clarified his statement by revealing his unity with the very animals she encountered. He explained, 'that dog which you saw suddenly, I have oneness with him. Similarly, the pig smeared with mud all over which you saw... I have oneness with him.' This illustrates that an act of kindness to any creature is an act of service directly to Baba.