WaltS,
this is meant just as a helpful tip; please don't take it as criticism. I really enjoy the game and don't find the dialogue or descriptions bad.
If you're going to use a well-known quote, I would suggest one of two things. If the quote was originally made in the English language, you should find the actual quote and use that. If the quote was translated into English from another language, find the most commonly accepted or distributed translation in English and go with that. (I would suggest the same for translations into other languages as well, of course.)
For instance, when quoting Isaac Newton's third law (esp. to tie the quote to the postman), the current in-game text (on the render and in the dialogue box) reads, "To every action there is always opposed an equal reaction".
That's a good and accurate translation. The original quote, however, made in English, was actually "to every action there is always an equal and opposite, or contrary, reaction", and the commonly used variant of that in English is "For every action, there is an equal and opposite reaction".
As another example, if you were to quote René Descartes' proof of self-existence, the original quote is in Latin ("Cogito, ergo sum") and was first translated as "je pense donc je suis" into French and from there into English as "I think, therefore I am". So, although it could also be rendered as "I think, so then I am", it sounds strange to an English audience who have learned it with "therefore" rather than "so then".