Joseph Fort Newton answers this question in the last paragraph of “The Builders”, probably the most popular of all Masonic books, in these words:
“When he can look out over the rivers, the hills and the far horizon with a profound sense of his own littleness in the vast scheme of things, and yet have faith, hope and courage, which is the root of every virtue. When he knows that down in his heart every man is as noble, as vile, as divine, as diabolic and as lonely as himself; and seeks to know, to forgive and to love his fellow man. When he knows how to sympathize with men in their sorrows, yea even in their sins – knowing that each man fights a hard fight against many odds. When he has learned how to make friends and to keep them and above all, how to keep friends with himself. When he loves flowers, can hunt birds without a gun and feels the thrill of an old forgotten joy when he hears the laugh of a little child. When he can be happy and high-minded amid the meaner drudgeries of life. When starcrowned trees and the glint of sunlight on flowing waters subdue him like the thought of one much loved and long dead. When no voice of distress reaches his ears in vain, and no hand seeks his aid without response. When he finds good in every faith that helps any man to lay hold of divine things and see majestic meanings in life, whatever the name of that faith may be. When he can look into a wayside puddle and sees something beyond mud, and into the face of the most forlorn fellow mortal and see something beyond sin. When he knows how to pray, how to love, how to hope. When he has kept faith with himself, with his God; in his hand a sword for evil, in his heart a bit of a song; glad to live, but not afraid to die! Such a man has found the only secret of Freemasonry, and the one which it is trying to give to all the world”.