A tidbit that occurred to me last night at the Shabbos table. :)
Commenting on the line in Yaacov's blessing for Yehuda that refers to a donkey (He will tie his donkey to the vine, to the vine branch his donkey's foal), Sforno contrasts a donkey to a horse: Whereas a horse is associated with war, a donkey represents "peaceful prosperity". The connotation is obvious- leadership, in the case of the tribe of Yehuda, will enjoy sufficient materialism and peace to enable them to focus on leading in a manner aligned with Hashem's ways. We see a parallel reference to a donkey in Yaacov's blessing of Yissachar (Issachar is a strong-boned donkey); since Yissachar is a tribe renowned for Torah scholarship, we see that the "strength" of the donkey, which outwardly is rooted in the material world, lies in its steadfast submission to its master's will, like the Torah scholar to his studies and, consequently, Hashem.
Earlier in the Torah, when learning of illegal combinations, a mule listed as one such prohibited mixture. A mule, as part horse and part donkey, demonstrates that when combined the positive traits of each becomes perverted: war and power (the horse), when linked to steadfastness (the donkey) results in the unceasing pursuit of materialism, which inevitably provokes disharmony. One only needs to look to the goyim to see that their leaders flaunt their power and wealth, to the detriment of their nations.
In sharp contrast, the secular leader of the Jewish nation must always steadfastly adhere to Hashem in his kingship of the land. By citing the donkey in his blessing of Yehuda, Yaacov reminds us all that adherence to a peaceful existence brings our lives to fruition both in this world- although we may not always see it- and the next. Only a nation that is ruled by a devotion to Hashem's values is a life, and a monarchy, worth having.