Some things I didn't understand in Justine

[Marchenoir]

That letter we can find in the Crypt...

http://amnesia.wikia.com/wiki/Crypt

"It all made sense, he thought, we all appreciate symmetry. Everyone is comforted by the causality of logic. It gives the impression of a grand plan and that we may be able to grasp the inner workings of this perfect universe.

You see, his wife had died while giving birth to his son. That is why he was able to forgive. His family was just giving in to the symmetry."

Wth is that supposed to mean? What is "making sense"? Who is his son (we never hear about him in game)? "Forgive" what? What kind of "symmetry" is he talking about?

Oh and a last thing. When Justine reads the slides in the library, she ends up every time with "today I'm the one who kneels, today I'm the one with the sword" etc what does it mean?

That's a lot of questions but could someone help me a bit?