Final answer:
Franklin added 'humility' to his list of virtues on the advice of a Quaker friend, and though 'mercy' is not part of his thirteen virtues, it is important to recognize humility's implied significance in his moral philosophy.
Step-by-step explanation:
According to Benjamin Franklin's Autobiography, the virtue added by Franklin after a Quaker friend pointed out that he might be lacking it was humility. Although this virtue is not explicitly listed in some presentations of Franklin's thirteen virtues, his friend's suggestion led him to give more emphasis to humility, which without pointing it out himself, he implies includes imitating Socrates and Jesus in his behavior. Franklin's list of virtues included: temperance, silence, order, resolution, frugality, industry, sincerity, justice, moderation, cleanliness, tranquility, chastity, and humility. The question has asked about multiple virtues, and it is worth noting that mercy was not one of the thirteen virtues specified by Franklin.