In the simplest example, playing of a cadence should be in relationship to the importance of that cadence in the overall form of the work. More important cadences are emphasized by pauses, dynamics, sustaining and so on. False or deceptive cadences are given some of the characteristics of a real cadence, and then this impression is undercut by going forward more quickly. For this reason, changes in performance practice bring changes to the understanding of the relative importance of various aspects of the sonata form. In the Classical era, the importance of sections and cadences and underlying harmonic progressions gives way to an emphasis on themes. The clarity of strongly differentiated major and minor sections gives way to a more equivocal sense of key and mode. These changes produce changes in performance practice: when sections are clear, then there is less need to emphasize the points of articulation. When they are less clear, greater importance is placed on varying the tempo during the course of the music to give "shape" to the music.