…Grund aus… / Auf Grund…
When do you use aus and when do you auf with the German noun for reason, der Grund?
This area can be tricky because sometimes, even though it’s the same word, you use different prepositions.
First of all: Grund means reason. Grund also means ground.
In English ground can also be the word for ‘reason’. “The grounds for the decision…”
With the reason(ing)/ground(s), it’s normal to use both, ‘on’ = ‘auf’, and ‘out of’ = ‘aus’.
Auf Grund schlechtes Wetter, haben sie nicht gespieltDankeschön, meine Schnecke : ).
On grounds of bad weather, they didn’t play.
Der Grund, aus dem er nicht dafür entschiedet hat, war ziemlich kompliziert.
The reasoning, out of which he decided against, are very complicated.
I had for a long time always used Auf. The error came from knowing the sentence structure, but misassociating the separate grammar from – Auf Grund – which is a common way to start a sentence. I hope this has made it crystal clear for you all out there, and that the correct preposition for each circumstance never evades you.