Different levels of mensuration have different roles in the musical structure. The most prominent one is the one corresponding to the compositional tactus. Rhythmic groups may contradict the mensuration temporarily, but in the examples in this book, they never do so throughout an entire piece.

hypersonic

With these protracted and unclockable events, a moment or date may be given when the goal has certainly not yet been reached, and another when it certainly has ; but it is impossible to come any closer to an exact moment within that period.

On the plains they will have horses dragging travoises, dogs with travoises, women and children loaded with impedimenta.