"A so-called happy marriage corresponds to love as a correct poem to an improvised song"

Karl Wilhelm Friedrich Schlegel's quote is a contrast between a happy marriage and a correct poem. He is suggesting that a happy marriage is like a proper poem, because it is thoroughly crafted and thoughtfully composed. A right poem is the outcome of hard work and devotion, and a happy marriage is no various. It takes effort and devotion to make a marriage work, and it is not something that can be improvised. An improvised song is spontaneous and typically lacks structure, whereas a proper poem is thoroughly constructed and has a clear structure. Schlegel's quote is a reminder that a happy marital relationship is not something that can be considered granted, however rather something that requires effort and commitment. It is a suggestion that an effective marriage is something that needs to be dealt with and nurtured in order to achieve success.