Webern's music, like that of both Brahms and Schoenberg, is marked by its emphasis on counterpoint and formal considerations; and Webern's commitment to systematic pitch organization in the twelve-tone method is inseparable from this prior commitment.[93] Webern's tone rows are often arranged to take advantage of internal symmetries; for example, a twelve-tone row may be divisible into four groups of three pitches which are variations, such as inversions and retrogrades, of each other, thus creating invariance.