Other common words of Norse derivation are _traill_, a slave; _nabuidh_, a neighbour; _sgillinn_, a penny; _mòd_, a court of justice, meeting; _gadhar_, a greyhound; _toraisgean_, a peat knife, half Norse, half Gaelic; _suith_, soot; _shearradair_, towel; _mal_, rent; _gleadhraich_, noise. The Vikings were called _sumarlidi_, “summer wanderers,” because they were most abroad at that season, and from this came the name once famous in the West—“Somerled” of the Isles. To the Norse is also attributed the insertion of _t_ in words like _struth_ for _sruth_, _stron_ for _sron_. V. But more important even than the introduction of new words was the influence upon the structure of the language. And competent authorities hold that to it we must assign the main share in accelerating the decay of inflection noticeable in the Scottish Gaelic and Manx as compared with the Irish. The latter was not so much exposed to Norse influence as the former. And it is very apparent that the change referred to began to assert itself soon after the Norse had ostracised the Irish, and taken its place as a rival language in the West, destined to influence the local Gaelic. It is not contended that the Gaelic writers derived any help from the Norsemen. They were themselves the more advanced of the two. On the other hand, the Icelandic scholar Viglisson has traced Gaelic rhymes and measures as well as Gaelic ideas in the old Norse literature, and Professor Zimmer even suggests that the Icelander owes to the Gael his prose style. In the Islendinga Book, c. 1., we read that when Iceland was first settled from Norway in the days of Harold Fairhair there were Christian men, whom the Norsemen called Papa, but who afterwards went away because they would not remain with the heathen, and left behind them Irish books and croziers and bells, from which it could be seen that they were Irishmen.[26] VI. How far the Norse ideas have entered into the warp and woof of Gaelic literature is perhaps the most interesting aspect of the whole subject, and one that offers a wide field for research. It cannot yet be said that we have sufficiently differentiated between the two sets of legends, beliefs, and customs to be able to affirm with certainty that such and such belong to the one race, and such and such belong to the other. The mythologies of peoples have so much in common, so much that seems characteristic of the thinking of the whole human race at certain stages of its development, that many ideas and legends have no exclusive value, and cannot be claimed as the original heritage of one people more than another.