 First, it follows from the basic idea of having a will that to act at all is to act on some principle, or what Kant calls a maxim. A maxim is a subjective rule or policy of action: it says what you are doing and why. Kant gives as examples the maxims “to let no insult pass unavenged” and “to increase my wealth by every safe means” (5:19, 27).  We may be unaware of our maxims, we may not act consistently on the same maxims, and our maxims may not be consistent with one another. But Kant holds that since we are rational beings our actions always aim at some sort of end or goal, which our maxim expresses. The goal of an action may be something as basic as gratifying a desire, or it may be something more complex such as becoming a doctor or a lawyer. In any case, the causes of our actions are never our desires or impulses, on Kant’s view. If I act to gratify some desire, then I choose to act on a maxim that specifies the gratification of that desire as the goal of my action. For example, if I desire some coffee, then I may act on the maxim to go to a cafe and buy some coffee in order to gratify that desire.