The characteristic ascending fourth opens the countersubject. To this, Beethoven adds a countersubject in dactylic rhythm (shown in red below). Here, Bach has altered the second countersubject to accommodate the change of mode. Their countersubject to the tenors' entry is a shimmering coloratura for more than three measures. The countersubject is written in invertible counterpoint at the octave or fifteenth. The countersubject usually contrasts with the subject/answer phrase shape. A countersubject enters immediately afterwards and is then used throughout the piece. The countersubject is the inversion of the theme, in German "" (reflection in a mirror).