Authors:

I have known some men possessed of good qualities which were very serviceable to others, but useless to themselves; like a sun-dial on the front of a house, to inform the neighbours and passengers, but not the owner within.

Jonathan Swift, David Laing Purves (1871). “The Works of Jonathan Swift, D.D.: Carefully Selected; with a Biography of the Author”, p.516
I have known some men possessed of good qualities which were very serviceable to others, but useless to themselves; like a sun-dial on the front of a house, to inform the neighbours and passengers, but not the owner