Isherwood was evidently anxious to convince the youth that the relationship he desired was that of lovers and friends rather than hustler and client; he felt possessive and was jealous of Bubi's professional contacts with other men, and the next day set off to resume his attempt to transform the rent boy into the Ideal Friend. Coached by Auden, whose conversational German was a good deal better than his own at this stage, he delivered a carefully prepared speech; he had, however, overlooked the Great Phrase-book Fallacy, and was quite unable to understand Bubi's reply.

-- Norman Page, Auden and Isherwood: The Berlin Years