been highly trained in dyadic counterpoint and thus possessed this and other information necessary to read a score correctly, even if the accidentals were not written in. As such, "what modern notation requires [accidentals] would then have been perfectly apparent without notation to a singer versed in counterpoint." (See musica ficta.) A singer would interpret his or her part by figuring cadential formulas with other parts in mind, and when singing together, musicians would avoid parallel octaves and parallel fifths or alter their cadential parts in light of decisions by other musicians. It is through contemporary tablatures for various plucked instruments that we have gained much information about which accidentals were performed by the original practitioners. For information on specific theorists, see Johannes Tinctoris, Franchinus Gaffurius, Heinrich Glarean, Pietro Aron, Nicola Vicentino, Tomás de Santa María, Gioseffo Zarlino, Vicente Lusitano, Vincenzo Galilei, Giovanni Artusi, Johannes Nucius, and Pietro Cerone. Composers – timeline Early period (1400–1470) The key composers from the early Renaissance era also wrote in a late Medieval style, and as such, they are transitional figures. Leonel Power (c. 1370s or 1380s–1445) was an English composer of the late medieval and early Renaissance music eras. Along with John Dunstaple, he was one of the major figures in English music in the early 15th century.) Power is the composer best represented in the Old Hall Manuscript, one of the only undamaged sources of English music from the early 15th century. Power was one of the first composers to set separate movements of the ordinary of the mass which were thematically unified and intended for contiguous performance. The Old Hall Manuscript contains his mass based on the Marian antiphon, Alma Redemptoris Mater, in which the antiphon is stated literally in the tenor voice in each movement, without melodic ornaments. This is the only cyclic setting of the mass ordinary which can be attributed to him. He wrote mass cycles, fragments, and single movements and a variety of other sacred works. John Dunstaple (or Dunstable) (c. 1390–1453) was an English composer of polyphonic music of the late medieval era and early Renaissance periods. He was one of the most famous composers active in the early 15th century, a near-contemporary of Power, and was widely influential, not only in England but on the continent, especially in the developing style of the Burgundian School. Dunstaple's influence on the continent's musical vocabulary was enormous, particularly