Published in 1914, The Builders by Brother Joseph Fort Newton contains one of the most eloquent and thoughtful answers to the question which has, no doubt, existed since the birth of speculative Freemasonry, "What is a mason?".  Because of the oratory skill and passion with which he wrote and ministered, one doesn't have to do much searching to find this passage from the end of section III, chapter 3 - The Spirit of Masonry quoted heavily throughout the Internet: 

When is a man a Mason? 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 the 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 star-crowned 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 sees majestic meanings in life, whatever the name of that faith may be. When he can look into a wayside puddle and see 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 fellow man, 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 real secret of Masonry, and the one which it is trying to give to all the world.

It is obvious that Brother Newton had great skill with his pen and a way with words that few possess.  It is for this reason that I offer you the rest of the chapter from which this quote is taken;  I promise you, it is equally as profound and reading it would be time well spent.

OUTSIDE of the home and the house of God there is nothing in this world more beautiful than the Spirit of Masonry. Gentle, gracious, and wise, its mission is to form mankind into a great redemptive Brotherhood; a league of noble and free men enlisted in the radiant enterprise of working out in time the love and will of the Eternal. Who is sufficient to describe a spirit so benign? With what words may one ever hope to capture and detain that which belongs of right to the genius of poetry and song, by whose magic those elusive and impalpable realities find embodiment and voice?

With picture, parable, and stately drama, Masonry appeals to lovers of beauty, bringing poetry and symbol to the aid of philosophy, and art to the service of character. Broad and tolerant in its teaching, it appeals to men of intellect, equally by the depth of its faith and its plea for liberty of thought--helping them to think things through to a more satisfying and hopeful vision of the meaning of life and the mystery of the world. But its profoundest appeal, more eloquent than all others, is to the deep heart of man, out of which are the issues of life and destiny. When all is said, it is as a man thinketh in his heart whether life be worth while or not, and whether he is a help or a curse to his race.

Here lies the tragedy of our race:
Not that men are poor;
All men know something of poverty.
Not that men are wicked;
Who can claim to be good?
Not that men are ignorant;
Who can boast that he is wise?
But that men are strangers!