The first opera season at the permanent theatre of Copenhagen in 1761-2, under the direction of Italian composer Giuseppe Sarti (1729-1802), was a complete fiasco, for both practical reasons and cultural clashes. Unlike anywhere else in Europe, Denmark discovered Italian opera only after the spread of Enlightenment thinking, promoting emergent forms of nationalism that surpassed former universalist perspectives. In Copenhagen, an aristocratic, cosmopolitan culture collided with a bourgeois, nationalist identity, which was rooted in local taste and ferociously opposed to Italian opera. Based on a letter that I recently discovered, this study focuses on Sarti’s solutions for adapting the genre for a foreign audience, from the perspective of opera in migration. The full text of the letter, which is written in French, is given in appendix with an English translation. First, Sarti focussed on the libretto translations, in order to address the criticism of excessive sensuality and theatricality, which had been levelled at opera as a genre. More importantly, he regarded the visual aspects (costumes, above all) as crucial tools for transmitting and adapting the genre to its new environment. Costumes were crucial visual signifiers and played a role even surpassing that of the sung text.