The purpose of this article is to discuss the classical demand in the “Groundwork” that an action to have moral worth has to be done from duty and not merely done in conformity with duty. I will be arguing that the main reason for this requirement is the reliability of producing the right action, and in order to show this I will put forward the example of what I call “the incorruptible ideal moral agent”. I will also suggest that the moral attitude required by Kant rather than being a puritanical view that undermines fellow feelings as moral motives to action, has an educative purpose and indicates the importance to adhere to a concept of reason in practical affairs that sharply challenges some practices and principles that are in vogue nowadays.