Note 9 — THE TONALAMATL AND THE SOLAR CALENDAR
Reading edition
Like the tonalamatl, the Venus period was productive of sacerdotal speculation, commencing with the day cipactli. At the end of six periods the Venus “year” recommenced with the same sign affected by a different figure. At the end of thirteen periods the sign differed, but the figure was the same. The question has been learnedly discussed in its entirety by Seler, to whose work the reader is referred.9