For example, they all know that when marching through an enemy’s country, the right way is to march in the formation in which they will fight best, if need be. Well, knowing this, some observe the rule, others break it.

All know that it is right to post sentries by day and night before the camp; but this too is a duty that some attend to, while others neglect it.

Again, where will you find the man who does not know that, in marching through a defile, it is better to occupy the points of vantage first? Yet this measure of precaution too is duly taken by some and neglected by others.

So, too, everyone will say that in agriculture there is nothing so good as manure, and their eyes tell them that nature produces it. All know exactly how it is produced, and it is easy to get any amount of it; and yet, while some take care to have it collected, others care nothing about it.

Yet the rain is sent from heaven, and all the hollows become pools of water, and the earth yields herbage of every kind which must be cleared off the ground by the sower before sowing; and the rubbish he removes has but to be thrown into water, and time of itself will make what the soil likes. For every kind of vegetation, every kind of soil in stagnant water turns into manure.