Category: calendars...

Norman Rockwell's Boy Scout calendar
making a photo calendar of family members
The calendar consents to carry on its dull wall-existence by the arbitrary timetables we have drawn up in consultation with those permanent commuters, Earth and Sun. (C. Fadiman)
I've been on a calendar, but never on time. (Marilyn Monroe)
Calendars and clocks exist to measure time, but that signifies little because we all know that an hour can seem an eternity or pass in a flash according to how we spend it. (M. Ende)
calendar comes from Latin calendarium "interest register, account book" from calendae, the first day of the Roman month, when market days, feasts, and other forthcoming events were announced
calendars evolved to measure periods for agricultural, business, domestic (etc.) reasons - the first known being that of the ancient Egyptians though the lunisolar formula was probably invented in Mesopotamia in the 3rd millennium BC