Leicher subsequently recalled that Strauss drafted two numbers for the work in the hospital immediately following the operation, after two cotton balls impregnated with a 2% cocaine solution had put him into such a state of stimulation that instead of resting he was inspired, and worked intensively.
The numbers were the duets Aber der Richtige, wenn’s einen gibt für mich and Und du wirst mein Gebieter sein, often described as the finest moments in the score.
This according to “Richard Strauss und die Hals-Nasen-Ohren-Heilkunde: Zur Entstehungsgeschichte der zwei schönsten Duette der Oper Arabella” by Herbert Pichler (Richard Strauss-Blätter I [June 1979] pp. 46–53).
Below, Aber der Richtige.