The same sunrise is counted in many ways. Below, one day is seen through the living calendars of humanity and through ancient ones still kept today, all computed live in your browser.
Notice what each calendar treats as certain. The Islamic and Hebrew calendars are watching the Moon; the Persian and Bahá'í, the equinox; the Chinese and Hindu, both at once; the Maya, a count of days with no end. The Codex is a place where all of these ways of seeing can meet.
Notes on accuracy: Islamic dates use the standard tabular rule, and local crescent sighting can differ by a day. Hindu dates are for India at sunrise and vary by region and tradition. The Hebrew, Islamic and Bahá'í days begin at sunset, so the evening before belongs to the date shown. Chinese dates use China's time zone.