资料题：The boatman was willing to take Robin across the river because（  ）。

It was not yet eleven o'clock when a boat crossed the river with a single passenger who had obtained his transportation at that unusual hour by promising m extra fare.While the youth stood on the landing place searching in his pockets for money, the ferryman lifted a lantern, by the aid of which, together with the newly risen moon, he took a very accurate survey of the stranger's figure.He was a young man of barely eighteen years, evidently county bred, and now, as it seemed, on his first visit to town.He was wearing a rough gray coat, which was in good shape,but had seen many winters before this one.The garments under his coat were well constructed of leather, and fitted tightly to a pair of muscular leg; his stockings of blue yam(纱线)must have been the work of a mother or sister, and on his head was a three-cornered hat, which in is better days had perhaps sheltered the gayer head of the lad's father.In his left hand was a walking stick, and his equipment was completed by a leather bag not so abundantly stocked as inconvenience the strong shoulders on which it hung.Brown, curly hair, well-shaped features,bright, cheerful eyes were nature's gits, and worth all that at could have done for his adornment(装饰).The youth, whose name was Robin, paid the boatman, and then walked forward into the town with a light step, as if he had not already traveled more than thirty miles that day.As he walked, he surveyed his surroundings as eagerly as if he were entering London or Madrid, instead of the little metropolis of a New English colony.