Eastern Orthodox liturgical calendar
The Eastern Orthodox liturgical calendar describes and dictates the rhythm of the life of the Eastern Orthodox Church. Passages of Holy Scripture, saints and events for commemoration are associated with each date, as are many times special rules for fasting or feasting that correspond to the day of the week or time of year in relationship to the major feast days.
Russian icon depicting the calendar of saints (18th-19th century).
The calendar of saints is the traditional Christian method of organizing a liturgical year by associating each day with one or more saints and referring to the day as the feast day or feast of said saint. The word "feast" in this context does not mean "a large meal, typically a celebratory one", but instead "an annual religious celebration, a day dedicated to a particular saint".
A medieval manuscript fragment of Finnish origin, c. 1340–1360, utilized by the Dominican convent at Turku, showing the liturgical calendar for the month of June
A Welsh calendar of saints' days, c. 1488–1498
Excerpt from the Irish Feastology of Oengus, presenting the entries for 1 and 2 January in the form of quatrains of four six-syllabic lines for each day. In this 16th-century copy (MS G10 at the National Library of Ireland) we find pairs of two six-syllabic lines combined into bold lines, amended by glosses and notes that were added by later authors.