“To me it seems that those who are happy in this world are better and more lovable people than those who are not.”

Source: The Way of All Flesh (1903), Ch. 26

Source: One Night @ the Call Center (2005), P. 248

In the case of the latter, I simply leave them to torment themselves trying to gain my sympathy.
Aleph (2011)

Vanity Fair (February 1920)
Variant: There may be said to be two classes of people in the world; those who constantly divide the people of the world into two classes, and those who do not.
Context: There may be said to be two classes of people in the world; those who constantly divide the people of the world into two classes, and those who do not. Both classes are extremely unpleasant to meet socially, leaving practically no one in the world whom one cares very much to know.

Humor in Psychotherapy (2007)

Il n'y a point de gens qui aient plus souvent tort que ceux qui ne peuvent souffrir d'en avoir.
Maxim 386.
Reflections; or Sentences and Moral Maxims (1665–1678)

Source: Professor Stewart's Cabinet of Mathematical Curiosities

2010s, Hard Truths: Law Enforcement (2015)