Do wrong to none

By loving all, you are opening your heart to all people, even to those who don’t love you, or who don’t have your best interests in their minds.
Which leads us to the next part of the quote. By trusting but a few, you are protecting yourself from those who are not worthy of your trust.
Finally, by refusing to do wrong to anyone, you help generate good-will and may even help win over some. It is also is the moral, ethical way to live your life.
Taken together, these three things make an excellent road-map for a happy and prosperous life.