"But what's wrong with combining virtue and pleasure?" our opponent asks. "Why can't we make the highest good from both honor and pleasure together?" Here's why: only what is honorable can be part of honor. The highest good would lose its purity if it contained anything unlike its best part. Even the joy that comes from virtue — though it's a good thing — isn't part of absolute good. Neither are cheerfulness or peace of mind. These are good things, but they just follow the highest good. They don't make it more perfect, even though they come from the noblest causes.
"But what," asks our adversary, "is there to hinder virtue and pleasure being combined together, and a highest good being thus formed, so that honour and pleasure may be the same thing?" Because nothing except what is honourable can form a part of honour, and the highest good would lose its purity if it were to see within itself anything unlike its own better part. Even the joy which arises from virtue, although it be a good thing, yet is not a part of absolute good, any more than cheerfulness or peace of mind, which are indeed good things, but which merely follow the highest good, and do not contribute to its perfection, although they are generated by the noblest causes.