So much of what is best in us is bound up in our love of family, that it remains the measure of our stability because it measures our sense of loyalty. All other pacts of love or fear derive from it and are modeled upon it.

This quote is explaining the importance of having strong family ties and how it can help you in life. It suggests that having a close, loving family is the sign of a stable life, and all the other relationships you form with friends, partners, or other family members are based off of the love and loyalty you already have within your family. The quote is suggesting that loving your family and being loyal to them is one of the most important things you can do in life.