Saint Ambrose has been celebrated as a Doctor of the Church. This rare designation is explained on Catholic Online in this way:

This is a very special title accorded by the Church to certain saints. This title indicates that the writings and preachings of such a person are useful to Christians “in any age of the Church.” Such men and women are also particularly known for the depth of understanding and the orthodoxy of their theological teachings. While the writings of the Doctors are often considered inspired by the Holy Spirit; [sic] this does not mean they are infallible, but it does mean that they contributed significantly to the formulation of Christian teaching in at least one area.

One claim to fame for Ambrose is that he is responsible for the conversion of (later-Saint) Augustine to Christianity.

Yet Ambrose’s pathway to the priesthood and the position of bishop was unconventional (and questionable), even by 4th-century standards. Ambrose was a governor of an area that encompasses present day Milan, Italy. There arose such a clatter in Milan–when their bishop (who was of the Arian heretical variety) died as to whether his successor should likewise be Arian or, instead, Athanasian (the latter eventually being ensconced as “orthodox”)–that Ambrose rushed there to see what was the matter.

And here is where Ambrose’s true brilliance shone: he was a natural-born mediator. He was able to meet with people whose positions were entrenched and who regarded those on the other side of their theo-political divide as Just Plain Evil. And Ambrose entered this conflict and listened to the people patiently, respectfully, and caringly. He foregrounded their commonality. Butler offers this description:

To prevent an open sedition, St. Ambrose thought it the duty of his office to go to the church in which the assembly was held: there he made an oration to the people with much discretion and mildness, exhorting them to proceed in their choice (of a new bishop) with the spirit of peace, and without tumult.

So for the Good: Ambrose was successful in encouraging the peaceful resolution of acrimony and conflict that was easily as white-hot (so to speak) as that between Trump’s most ardent supporters and Trump’s most vociferous critics.

A child present at that church conference in Milan (reminiscent of the child in Hans Christian Andersen’s “The Emperor’s New Clothes”) called out something to the effect of “Make Ambrose Bishop!!!” And all who gathered unanimously proclaimed that Ambrose should take over the See!

Now for the Bad: What followed was chaotic, inasmuch as Ambrose wasn’t even a baptized Christian at that point! And he had absolutely zero desire to become a bishop. So he fled the Milanese, asked for a position as a judge, and then set about conducting himself as a ruthless, unscrupulous “hanging judge” who subjected prisoners to extreme and disproportionate torture and worked overtime toward garnering a reputation of being the antithesis of “good church leadership material.” The result? Ambrose continued to be hounded by the Milanese (and then by Rome) into getting baptized and almost immediately being made a bishop! Yes. Within days: Someone with no church experience and no desire for the job who turns to the torture of others to convince others of his poor character is suddenly Bishop Ambrose!

Oh, and for the Ugly? This is already mentioned, above–Ambrose shepherded Augustine into the ranks of Christianity.