What is the use of all knowledge, if one does not act in accordance with it? This remark implies that knowledge is regarded as a means to action, and the latter as the real end. One could put the question the other way round and ask: How can we possibly act well without knowing what the Good is? This way of expressing it would regard knowledge as conditioning action. But both expressions are one-sided, and the truth is that both, knowledge as well as action, are in the same way inseparable elements of rational life.