How did the sight of a newborn calf help Sal cope with life after her mother left?

The sight of the newborn calf made Sal realize that she could be happy without her mother.

One day, about two weeks after she had left, I was standing against the fence watching a new-born calf wobble on its thin legs. It tripped and
wobbled and swung its big head in my direction and gave me a sweet, loving look. 'Oh!' I thought. 'I am happy at this moment in time.' I was surprised that I knew this all by myself, without my mother there. And that night in bed, I did not cry. I said to myself, 'Salamanca Tree Hiddle, you can be happy without her.' It seemed a mean thought and I was sorry for it, but it felt true.