Record of the development of the Egyptian calendars show they kept record of wet and rainless periods, through the behaviour of the river Nile. Later on, two calendars were developed. The Lunar Calendar had basically a religious purpose. The beginning of the month was marked by the morning when the crescent moon could no longer be seen. The month may have been divided into four periods of 7 or 8 days. It was used by various cults, until the closing of the Egyptian pagan temples under the Byzantines. A Civil Solar Calendar was established, based on the star observations that corresponded to the Nile flood. This calendar was divided into 12 months of 30 days each. It also served to keep a record of religious celebrations. Both calendars show a close connection between nature - constellations, the Nile and its behaviour, religion, and how these aspects affected their everyday life.
