“There is no man so friendless but what he can find a friend sincere enough to tell him disagreeable truths.”

The quote may address the half of it. A nature's law absolute begins to address another half or potion. Luke 16:9 comes to mind. "And I say unto you, Make to yourselves friends of the mammon of unrighteousness; that, when ye fail, they may receive you into everlasting habitations."