The article offers a diachronic view of the signs in Czech sign language for the twelve months of the year and seven days of the week. It looks at the original motivation for these signs, which can be traced back in written sources of the 19th century and it determines the area of everyday life from which the signs for the calendar units are derived.
The probable original motivation is compared with the results of synchronic research into the motivation of signs from the perspective of folk etymology.