In grouping his Lieder into sets with opus numbers, Brahms was concerned with thematic unity and poetic contrasts. The theme of Op. 71 is love, whether ardent, ironic or courtly, and contains one of his best-loved songs, Minnelied. In Op. 70 the connections are more subtle: past, present and future create the thematic framework. The serenity of Op. 95 is heightened through the use of Serbian folk songs, and for the Op. 107 set Brahms once again illuminates love in all its intensity and humour.