“Erotic play discloses a nameless world which is revealed by the nocturnal language of lovers. Such language is not written down. It is whispered into the ear at night in a hoarse voice. At dawn it is forgotten.”

A Thing About You
Lyrics, Hard Promises (1981)

Answer to a survey written by the French mathematician Jaques Hadamard, from Hadamard's An Essay on the Psychology of Invention in the Mathematical Field (1945). Reprinted in Ideas and Opinions (1954). His full set of answers to the questions can be read on p. 3 here http://www.pitt.edu/~jdnorton/Goodies/Einstein_think/index.html.
1940s
Context: The words or the language, as they are written or spoken, do not seem to play any role in my mechanism of thought. The psychical entities which seem to serve as elements in thoughts are certain signs and more or less clear images which can be "voluntarily" reproduced and combined. There is, of course, a certain connection between those elements and relevant logical concepts. It is also clear that the desire to arrive finally at logically connected concepts is the emotional basis of this rather vague play with the above-mentioned elements.... The above-mentioned elements are, in my case, of visual and some muscular type. Conventional words or other signs have to be sought for laboriously only in a secondary stage, when the mentioned associative play is sufficiently established and can be reproduced at will.

O guiding night! O night more lovely than the dawn!
O night that has united the Lover with his beloved, transforming the beloved in her Lover.
Variant translation by Kieran Kavanaugh and Otilio Rodriguez (1991)
Oh night thou was my guide
Oh night more loving than the rising sun
Oh night that joined the lover to the beloved one
transforming each of them into the other.
Variant adapted for music by Loreena McKennitt (1994)
Dark Night of the Soul

Source: The Great Gatsby

The Soldier's Dream http://www.bartleby.com/106/267.html

The Saviors of God (1923)
Context: All hopes and despairs vanish in the voracious, funneling whirlwind of God. God laughs, wails, kills, sets us on fire, and then leaves us in the middle of the way, charred embers.
And I rejoice to feel between my temples, in the flicker of an eyelid, the beginning and the end of the world.
I condense into a lightning moment the seeding, sprouting, blossoming, fructifying, and the disappearance of every tree, animal, man, star, and god.
All Earth is a seed planted in the coils of my mind. Whatever struggles for numberless years to unfold and fructify in the dark womb of matter bursts in my head like a small and silent lightning flash.
Ah! let us gaze intently on this lightning flash, let us hold it for a moment, let us arrange it into human speech.
Let us transfix this momentary eternity which encloses everything, past and future, but without losing in the immobility of language any of its gigantic erotic whirling.

Source: When Women Were Birds: Fifty-four Variations on Voice

1920s, Tractatus Logico-Philosophicus (1922)
Context: This remark provides the key to the problem, how much truth there is in solipsism. For what the solipsist means is quite correct; only it cannot be said, but makes itself manifest. The world is my world: this is manifest in the fact that the limits of language (of that language which alone I understand) mean the limits of my world. (5.62)

Vol. I, Ch. III, The World As Representation
The World as Will and Representation (1819; 1844; 1859)
Context: The composer reveals the innermost nature of the world, and expresses the profoundest wisdom in a language that his reasoning faculty does not understand, just as a magnetic somnambulist gives information about things of which she has no conception when she is awake. Therefore in the composer, more than in any other artist, the man is entirely separate and distinct from the artist.