This paper offers an investigation into the interface between science, in the form of astronomy, and culture, in the form of religion and the calendar. Early societies made use of a variety of mechanisms to mark time, based on the cycles of the sun, moon and stars, whether separately or in combination. In this paper I provide a survey of the use of one of these cycles, namely that of the stars, in one ancient culture, that of the Greeks. I show how gradually the night sky was mapped out with a number of distinct constellations, the number increasing over time. The Greeks used the first and last visible risings and settings of these stars at dawn and dusk as ‘event markers’, in order to signal the appropriate time for pivotal activities, especially in the agricultural sphere, such as ploughing, sowing and harvesting. At the same time, Greek societies used the moon as the basis for their civil and religious calendar, and within the lunar months were situated regular festivals of an agricultural nature. Agriculture is tied to the seasons and hence the sun, which the star cycle matches fairly well, but the moon runs on a different cycle which does not keep pace with the sun and stars. The increased refinement of the star calendars with a larger number of constellations might be a result of a desire to help synchronise the divergent seasonal and lunar timetables. Examples are provided to illustrate how particulars stars might have been associated with particular divinities and festivals.