behold , the guile of that gnome was very great , for he wrought much in the dark , so that folk said : `` he doth well to bear the sign of a sable mole '' ; and by reason of the folly of certain of the quarrymen , and yet more by reason of the loose words of certain among his tin to whom word was somewhat unwarily spoken by tuor , he gathered a knowledge of the secret work and laid against that a plan of his own .