Q:In re: Perlen vor die Säue werfen - "casting pearls before swine" is an expression in English too. It's a Bible thing, if memory serves. Just an FYI. :)
It is a Bible thing indeed! It’s from Matthew 7:6 (or Matthäus 7,6 in German) and became popular after Martin Luther translated the Bible to German.
There are actually a number of German proverbs and expressions that originate from the Bible, for example →Wer andern eine Grube gräbt, fällt selbst hinein. is from Ecclesiastes 10:8.
When I created this blog, I was thinking about adding the origins of proverbs, as far as I knew them or was able to research, but then I decided against it for I thought it would not be of interest to the majority of my potential followers and quite a lot of work for that. But if you or anyone would be interested in these origins, please let me know via reply or ask, I might add them now.