Almost surprising that the pessimistic philosophy of Schopenhauer entails such a morality:
"... the appropriate form of address between man and man ought to be, not monsieur, sir but fellow sufferer, compagnon de misères. However strange this may sound it corresponds to the nature of the case, makes us see other men in a true light and reminds us of what are the most necessary of all things: tolerance, patience, forbearance and charity, which each of us needs and which each of us therefore owes."
Arthur Schopenhauer, Essays and Aphorisms
(Translated from Parerga and Paralipomena by R. J. Hollingdale)