Langer correctly assumed that the Germans would make further modifications to the Enigma machine, and he provided Rejewski only with a commercial machine, wanting his cryptologists to understand the machine from a purely mathematical point of view.
The Germans would make further modifications to the Enigma machine. This was what Langer assumed. He provided Rejewski only with a commercial machine. He was wanting his cryptologists. This was to understand the machine from a purely mathematical point of view.