 The arts of manuscript illumination , <unk> and sculpture flourished and produced treasures such as the Book of Kells , ornate jewellery and the many carved stone crosses that still dot the island today . A mission founded in <unk> on Iona by the Irish monk Saint Columba began a tradition of Irish missionary work that spread Celtic Christianity and learning to Scotland , England and the Frankish Empire on Continental Europe after the fall of Rome . These missions continued until the late Middle Ages , establishing monasteries and centres of learning , producing scholars such as <unk> <unk> and Johannes <unk> and <unk> much influence in Europe . 
