Professor Barnet noted that in Act 1, scene 7, Mac says: "Prithee, peace! / I dare do all that may become a man; / Who dares no more is none." He goes on to inform us that since the time of Samuel Johnson, editors have replaced "no" with "do:" "Who dares do more is none." It seems to me that Barnet chose this passage as an example because he found it interesting. It also seems that Macbeth is defending his previous statement: " I have bought / Golden opinions from all sorts of people, / Which would be worn now in their newest gloss, / Not cast aside so soon." In other words, he would like to continue wearing his "Golden opinions" even though it seems silly or cowardly. Therefore, "no" is ok. Would anyone like to argue or explain why "do" is better?