"How is it they live in such harmony the billions of stars - when most men can barely go a minute without declaring war in their minds about someone they know"

Thomas Aquinas is suggesting that the stars, which are so many and diverse, have the ability to reside in consistency in spite of their differences. This remains in stark contrast to human beings, who often struggle to get along with one another, even those they understand. He is suggesting that human beings can much more than they frequently demonstrate, which if we could discover to live in harmony like the stars, we would be much better off. He is likewise recommending that humans often declare war in their minds versus those they understand, which suggests our inability to get along. This quote serves as a tip that we must make every effort to be more like the stars, and to find out to reside in consistency with one another, despite our distinctions.