Most, but not all, Aesop's fables have some kind of moral, a lesson or message which the fable teaches. Here are the different kinds of morals you might find in a fable:
Promythium: This is the moral that comes before the fable (pro-mythium, “before-story”).
Epimythium: Much more common is the epimythium, the moral that comes after the fable (epi-mythium, “after-story”). In English, the epimythium is often introduced with this formula: “... and the moral of the story is ...”
Endomythium: This is the moral that is inside the story, spoken by one of the characters (endo-mythium, “inside-story”). Although the term endomythium is not found in the standard literary handbooks, you will see that this is the most common form for a moral to take, something that feels very much like the punchline of a joke.
In selecting the fables for this book, I have preferred the versions that have an endomythium. As for the promythia and epimythia, I have sometimes included them, and sometimes not, based on whether they seemed to make a useful contribution to the story. I have not gone so far as Lloyd Daly, the author of Aesop Without Morals, who expunged all the promythia and epimythia from the fables as unwelcome editorial intrusions. I agree with Daly's impulse, but in some cases the epimythia are quite witty or insightful, and so I have included many of them here.
Most importantly, you should feel free to make up your own morals for the stories; moraliza sicut vis, as one of the medieval fabulists says (see Hervieux, vol. 4:411). The fables are meant to be applied in real life, and that means in your life, too. It's up to you to explore the different possible morals and life lessons that lurk in every fable. So, if the fable does not have a moral, invent one. If the fable already has a moral, you can change it. After all, as the fable of the ploughshares tells us (#760), these stories need to be used in order to stay sharp!