Whenever we do anything, we are trying to get something done. Why? Because we think that it somehow will be good for us to have done it. So it is said that "the good" is what everything tries to get at. But what that means is different for different things.

Sometimes we do one thing so that we can then go and do something else. Other times we do something so that we can have something. We think that having something is naturally better than being able to do something.

Now, there are many things that people do [actions], many ways of getting things done [arts], and many things to know about [sciences]. Each of these is different and has a different point to it. For example, the point of learning and practicing medicine is to make people healthy. Medicine is different from shipbuilding. The point of learning how to build a boat and then building a boat is in order to have a boat. The point of learning how to make strategies and then carry them out is in order to win. The point of learning economics and then making economical decisions is in order to get money.

However, in cases where many different things go towards the same one thing, then that one thing that they all go towards is a greater thing than any of the many things that go into it. For instance, people need equipment to ride horses and so other people learn to make each of the pieces of equipment (viz. a bridle and a saddle). Riding a horse is a greater thing than either making a bridle or making a saddle. Likewise, people ride horses in calvary charges and that is one kind of military action. There are other military actions, and together they are all part of strategy. So the whole strategy of the army is greater than riding a horse or making a camp.

Now, why do we say these things are greater? Because the reason why someone makes a bridle is so that someone else can ride a horse. People do not ride horses in order for bridles to get made. It does not really matter whether what we are talking about is the doing of something (e.g. riding a horse) or the having of something (e.g. owning a car). If we are trying to get done something (e.g. make a bridle) because that thing is going to be for something else (e.g. riding a horse), then the thing that we do it for is greater.