Such a calendar was presented by Onasanya (2009) in his The Urgency of Now!: Building a True Nigerian Nation.[2] Many parts of this calendar are named for or dedicated to certain spirits (Igbo: Mmuo) and deities (Igbo: Alusi) in Igbo mythology. Some of the spirits and deities were believed to have given the Igbo people knowledge of time. The days, also known as market day, also correspond to the four cardinal points, north, south, east, west.