Gradually the viking life assumed a nobler form. There appear to have been three stages or periods in the viking age. In the first one the vikings make casual visits with single ships to the shores of England, Ireland, France or Flanders, and when they have plundered a town or a convent, they return to their ships and sail away. In the second period their cruises assume a more regular character, and indicate some definite plan, as they take possession of certain points, where they winter, and from where they command the surrounding country. During the third period they no longer confine themselves to seeking booty, but act as real conquerors, take possession of the conquered territory, and rule it. As to the influence of the Northmen on the development of the countries visited in this last period, the eminent English writer, Samuel Laing, the translator of the _Heimskringla_, or the Sagas of the Norse kings, says: "All that men hope for of good government and future improvement in their physical and moral condition--all that civilized men enjoy at this day of civil, religious, and political liberty--the British constitution, representative legislation, the trial by jury, security of property, freedom of mind and person, the influence of public opinion over the conduct of public affairs, the Reformation, the liberty of the press, the spirit of the age--all that is or has been of value to man in modern times as a member of society, either in Europe or in the New World, may be traced to the spark left burning upon our shores by these northern barbarians." The authentic history begins with Halfdan the Swarthy, who reigned from the year 821 to 860. The Icelander Snorre Sturlason, who, in the twelfth century, wrote the _Heimskringla_, or Sagas of the Norse Kings, gives a long line of preceding kings of the Yngling race, the royal family to which Halfdan the Swarthy belonged; but that part of the Saga belongs to mythology rather than to history. According to tradition, the Yngling family were descendants of Fiolner, the son of the god Frey. One of the surnames of the god was Yngve, from which the family derived the name Ynglings. King Halfdan was a wise man, a lover of truth and justice. He made good laws, which he observed himself and compelled others to observe. He fixed certain penalties for all crimes committed. His code of laws, called the Eidsiva Law, was adopted at a common _Thing_ at Eidsvol, where about a thousand years later the present constitution of Norway was adopted.