She can't owe it to him.

_Voyons_, Saupiquet, if you don't renounce your miserable pretensions you will drive me mad, you will make me burst into tears, you will make me throw you out into the street, and hold you down until you are run over by a tramcar.

You will--you will"-- he shook his fist passionately as he sought for a climactic menace--"you will make me spit in your eye." He dashed his fist down on the marble table so that the glasses jingled.
Saupiquet finished his cognac undisturbed.
"I say that Madame Brandt owes me fifteen sous, and until that is paid, I do no business." The little man grew white with exasperation, and his upper lip lifted like an angry cat's, showing his teeth.

I shrank from meeting Saupiquet's eye.

Hurriedly, I drew a providential handful of coppers from my pocket.
"Stop, Herr Professor," said I, eager to prevent the shedding of tears, blood, or saliva, "I have just remembered.