During this period also, probably within a year after the death of his son William, Henry took measures to establish the position of one of his illegitimate sons, very likely with a view to the influence which he might have upon the succession when the question should arise. Robert of Caen, so called from the place of his birth, was created Earl of Gloucester, and was married to Mabel, heiress of the large possessions of Robert Fitz Hamon in Gloucester, Wales, and Normandy. Robert of Gloucester, as he came to be known, was the eldest of Henry's illegitimate sons, born before his father's accession to the throne, and he was now in the vigour of young manhood. He was also, of all Henry's children of whom we know anything, the most nearly like himself, of more than average abilities, patient and resourceful, hardly inheriting in full his father's diplomatic skill but not without gifts of the kind, and earning the reputation of a lover of books and a patron of writers. A hundred years earlier there would have been no serious question, in the circumstances which had arisen, of his right to succeed his father, at least in the duchy of Normandy. That the possibility of such a succession was present in men's minds is shown by a contemporary record that the suggestion was made to him on the death of Henry, and rejected at once through his loyalty to his sister's son. Whether this record is to be believed or not, it shows that the event was thought possible.[23] Certainly there was no real movement, not even the slightest, in his favour, and this fact reveals the change which had taken place in men's ideas of the succession in a century. The necessity of legitimate birth was coming to be recognized as indisputable, though it had not been by the early Teutonic peoples. Of the causes of this change, the teachings of the Church were no doubt the most effective, becoming of more force with its increasing influence, and especially since, as a part of the Hildebrandine reformation, it had insisted with so much emphasis on the fact that the son of a married priest could have no right of succession to his father's benefice, being of illegitimate birth; but the teachings of the sacredness of the marriage tie, of the sinfulness of illicit relations, and of the nullity of marriage within the prohibited degrees, were of influence in the change of ideas. It is also true that men's notions of the right of succession to property in general were becoming more strict and definite, and very possibly the importance of the succession involved in this particular case had its effect. One may almost regret that this change of ideas, which was certainly an advance in morals, as well as in law, was not delayed for another generation; for if Robert of Gloucester could have succeeded on the death of Henry without dispute, England would have been saved weary years of strife and suffering.