i think the most important theme in the play is honour. honour is both a motif and a theme in the play. thequestion of prince harry's honour as compared to his foil hotspur. this honour follow through the play as we his honour later improve has he was only putting on a show, that is he gave a false impression before giving his real one which is shown when he defeated hotspur. hence a next dramatic imegery, appearance v.s reality is brought out. remembering that king henry the iv is a historical play, we also see king henry's honour being questioned, that is he commited regicide.