WIST

Whatever tears one may shed, in the end one always blows one’s nose.

Heinrich Heine (1797-1856) German poet and critic
(Attributed)
Quoted in Simone de Beauvoir, Memoirs of a Dutiful Daughter, bk. 3 (1958, tr. 1959).

Experience is a good school. But the fees are high.

Heinrich Heine (1797-1856) German poet and critic
(Attributed)

One should forgive one’s enemies, but not before they are hanged.

Heinrich Heine (1797-1856) German poet and critic
(Attributed, 1848)
Alt trans: "One must forgive one's enemies, but not before they are hanged."

Wherever they burn books they will also, in the end, burn human beings.

[Dort, wo man Bücher verbrennt, verbrennt man auch am Ende Menschen.]

Heinrich Heine (1797-1856) German poet and critic
Almansor: A Tragedy, l. 245 (1823)

Alt trans:

Where they burn books, at the end they also burn people.
Where they burn books, they will also burn people.
It is there, where they burn books, that eventually they burn people.
Where they burn books, so too will they in the end burn human beings.
Where they burn books, they also burn people.
Them that begin by burning books, end by burning men.
Wherever books are burned, sooner or later men are also burned.

People in those old times had convictions; we moderns only have opinions. And it needs more than a mere opinion to erect a Gothic cathedral.

Heinrich Heine (1797-1856) German poet and critic
Französische Bühne [The French Stage], ch. 9 (1837)

Oh what lies there are in kisses!
And their guile so well prepared!
Sweet the snaring is; but this is
Sweeter still, to be ensnared.

Heinrich Heine (1797-1856) German poet and critic
The Home-coming, Poem 74

Of course God will forgive me; that’s his job.

[Bien sûr, il me pardonnera; c'est son métier.] 

Heinrich Heine (1797-1856) German poet and critic
Last Words (1856)

Quoted in German in Alfred Meißner, "Heinrich Heine. Erinnerungen," Letzte Worte auf dem Totenbett (1856). 
Quoted in Bros. Goncourt (ed.) Journal (23 Feb 1863). 
Quoted in French in Sigmund Freud, The Joke and Its Relation to the Unconscious (1905) [tr. J Crick (2003)] 

Alt trans.:
Why, of course, he will forgive me; that's his business.
Gott wird mir verzeihen, das ist sein Beruf.