The days of the month were expressed in early Latin using the ablative of time, denoting points in time, in the contracted form "the 6thDecember Kalends" ('). In classical Latin, this use continued for the three principal days of the month but other days were idiomatically expressed in the accusative case, which usually expressed a duration of time, and took the form "6th day before the December Kalends" ('). This anomaly may have followed the treatment of days in Greek, reflecting the increasing use of such date phrases as an absolute phrase able to function as the object of another preposition, or simply originated in a mistaken agreement of ' with the preposition ' once it moved to the beginning of the expression. In late Latin, this idiom was sometimes abandoned in favor of again using the ablative of time.