Unusually among European epic cycles, the Irish sagas were written in prosimetrum, i.e. prose, with verse interpolations expressing heightened emotion. Although usually found in manuscripts of later periods, many of these works are feature language that is older than the time of the manuscripts they are contained in. Some of the poetry embedded in the tales is often significantly older the tale it is contained in. It is not unusual to see poetry from the Old Irish period in a tale written in principally in Middle Irish.