Honey is not sweeter in your mouths, and light is not more pleasant to your eyes, and music to your ears, and a warm, cosey bed is not more welcome to your wearied legs and head, than is the honest, deep gratitude of the poor to the young Doctor. It is his glory, his reward; he fills himself with it, and wraps himself all round with it as with a cloak, and goes on in his work, happy and hearty; and the gratitude of the poor is worth the having, and worth the keeping, and worth the remembering. Twenty years ago I attended old Sandie Campbell's wife in a fever, in Big Hamilton's Close in the Grassmarket,--two worthy, kindly souls they were and are. (Sandie is dead now.) By God's blessing, the means I used saved "oor Kirsty's" life, and I made friends of these two forever; Sandie would have fought for me if need be, and Kirsty would do as good. I can count on them as my friends, and when I pass the close-mouth in the West Port, where they now live, and are thriving, keeping their pigs, and their hoary old cuddie and cart, I get a courtesy from Kirsty, and see her look after me, and turn to the women beside her, and I know exactly what she is saying to them about "Dr. Broon." And when I meet old Sandie, with his ancient and long-lugged friend, driving the draff from the distillery for his swine, I see his gray eye brighten and glisten, and he looks up and gives his manly and cordial nod, and goes on his way, and I know that he is saying to himself, "God bless him! he saved my Kirsty's life," and he runs back in his mind all those twenty past years, and lays out his heart on all he remembers, and that does him good and me too, and nobody any ill. Therefore, give your gratitude to your Doctor, and remember him, like honest Sandie; it will not lose its reward and it costs you nothing; it is one of those things you can give and never be a bit the poorer, but all the richer. One person I would earnestly warn you against, and that is the _Quack Doctor_. If the real Doctor is a sort of God of healing, or rather our God's cobbler for the body, the Quack is the Devil for the body, or rather the Devil's servant against the body. And like his father, he is a great liar and cheat. He offers you what he cannot give. Whenever you see a medicine that cures everything, be sure it cures nothing; and remember, it may kill. The Devil promised our Saviour all the kingdoms of the world if he would fall down and worship him; now this was a lie, he could not give him any such thing. Neither can the Quack give you his kingdoms of health, even though you worship him as he best likes, by paying him for his trash; he is dangerous and dear, and often deadly,--have nothing to do with him.