Let his conscience and virtue be eminently manifest in his speaking, and have only reason for their guide. Make him understand, that to acknowledge the error he shall discover in his own argument, though only found out by himself, is an effect of judgment and sincerity, which are the principal things he is to seek after; that obstinacy and contention are common qualities, most appearing in mean souls; that to revise and correct himself, to forsake an unjust argument in the height and heat of dispute, are rare, great, and philosophical qualities.