Lyric discussion by nummerzwei 

Cover art for Kreise lyrics by Wir Sind Helden

I honestly wonder if this song is about a mathematician, given the references to both cryptography ('unsichtbare Botschaften zu schreiben') and geometry ('Kreise'). But I study math, so it might be me. It also refers to some taxi drivers :). As possible literary influences I'll note Rilke's poem, 'Der Panther' and Marlen Haushofers 1963 novel 'The Wall'.