For anything we have to take and somehow handle, we have two vices and a virtue. We can think of them as being stances we can take. Each them stands opposed to both the other two. (You can think of stances like the stances you take in sports. When you take a stance you are ready for certain kinds of action. Different stances make you ready for taking different actions.)

With things set up like this, the biggest difference lies between the two extremes (the vices), each of them is most against the other one, and not as much against the mean (the virtue). So think about three temperatures: too hot, too cold, and just right; too hot and too cold are farthest away from each other, and each is closer to just right. Or to put it another way: each of the extremes (the vices) is like the mean (the virtue) in some kind of way, but when compared with each other, the vices are very much unlike.

For instance, a brave person may seem like as if they were rash from the point-of-view of a coward, and someone that is prodigal may look as if they were liberal from the point-of-view of a stingy person. But prodigality and meanness, cowardice and rashness are totally unlike each other; nobody would mix them up and think, for instance, that someone who blew a lot of money on an expensive dinner was being stingy. For things that are contrary, you can see a difference between them, and things that are more contrary have a bigger difference. So we can see it makes sense that the two vices are more contrary to each other, they have a bigger difference between them, and are more unlike each other than the mean (the virtue).

The mean (the virtue) does not always come exactly in between the vices. The mean will often be farther away from one of the vices than the other. Sometimes the mean is more against the deficiency; courage is more against cowardice (the deficiency) than it is against recklessness (the excess). Sometimes it is other other way around: the mean is more against the excess; a temperate person is more like an uptight (deficient) person than a self-indulgent (excessive) one.

This happens for two reasons: (1) how we see the things as compared against each other and (2) how we see them when compared with ourselves.

(1) It can be that one of the ways to go wrong can look as if it were the right way because it is not wrong in the really bad way. For example, imagine you are going out to eat and it is your turn to pay. What is the worst thing you can do? To be stingy and not let people order things that are reasonably priced (or even to try to get out of paying). OK, now imagine you order things that are way too expensive for your budget and are not normal. That actually is not right to do, and it is called being prodigal. But if you think about doing that when compared with being stingy, it can look as if you are doing the right thing, because it is the opposite of the worst thing. But really they are both wrong even though they are both opposite of each other. The right thing is to be liberal, and that is not exactly in the middle, but rather it is closer to prodigality and farther away from meanness.

(2) The other reason is in cases where we more easily fall into one of the vices, and we know this, and so we try harder to get away from it. In those cases, we make the mean be farther away from the thing we are always trying to get away from. For instance, for most of us, we are more worried about being too self-indulgent than we are worried about being too uptight. Being too self-indulgent is easier to fall into and also it is more dangerous (viz. it can be bad for the health). So we think of being temperate as being something that should be far away from being self-indulgent. By thinking about it like this, we hope to avoid making a mistake where we tell ourselves that we are being temperate in allowing ourselves to have something (e.g. "ok, just one"), but really that is an excuse and we are actually being too self-indulgent. On the other hand, as far as being too uptight goes, it is not so easy to fall into doing that by a mistake. So we are not so worried about it, and not so worried about putting the mean (temperance) closer to uptightness.