A fable is a short, realistic tale, which seeks to teach us some moral or virtue, and thus improve our conduct. This advice is cloaked in the interactions of animals of the field, birds of the air, trees of the wood, and beasts of the forest, so that we do not notice the presence of the adviser.
The lesson of the fable is thus easy to accept, as we are spared the superiority of the counselor. It is easy to accept a lesson when, unconsciously, our sympathies are enlisted for the pure, honorable, and praiseworthy, and our indignation is raised against what is low, ignoble, and unworthy.
Through listening to a simple and engaging story - our morals are easily improved, our vices curbed, and our virtues strengthened.
Each fable should speak for itself - accordingly my commentary is minimal