For daily readings there are two separate Cycles, Year One and Year Two. The prescribed readings are called the Lectionary. The Lectionary also has prescribed readings for Holy Days, Saints days and other important days in the Christian year. In the Christian calendar August 6 is the Feast of the Transfiguration, when our Lord appeared in glory during His earthly life. Matthew, Mark, and Luke all relate this story.
Scholars disagree about the location of the event.
Regardless of where it took place, it was a momentous, miraculous event which confirmed the Jewish law and prophets and affirmed the messiahship of Christ. When August 6 falls on a Sunday the readings for the Transfiguration take precedence over the readings listed in the Lectionary. This directive is found on Page 16 of the prayer book. The process of significant events being officially observed in the church is an interesting one. Although three gospels carry this story, it seems to have been celebrated at first by local congregations.