Visit the A crotchety old man in the Thieves' Forest give him 1 gold and he will tell you that is not the amount he wants, he will then tell you how large an amount of gold he requires. Give him that amount to gain the mark.
Note: The amount only seems to change when he has received an amount asked for.
For seeking out your elders for advice, the Powers granted thee a Mark. You have been granted The Mark of Insight! You gain 55 practices!