Quote about judging "a man by his post" from the City of God, according to Alain de Botton A few years ago, the philosopher Alain de Botton gave a TED talk on "A kinder, gentler philosophy of success" where he quotes St. Augustine supposedly having written in the City of God that "It's a sin to judge any man by his post" though he declares himself to be a "secular" person.

I have just finished my year-long reading the City of God and found no explicit statement about judging someone by their profession.  I did find Augustine listing what he means by sin close to the end of the reading (eg. books 20 and 22) but I became curious how Alain de Botton came to this interpretation.

Could this be a misattribution?
The Ox lists honoring a man (as opposed to God) as one of his objections to honoring those in places of dignity , but I don't know what he's talking about in book 10 of City of God maybe someone else can find it.
But here's what Aquinas says about it in the Summa

Objection 1.
It seems that it does not belong to observance to pay worship and honor to persons in positions of dignity. For according to Augustine (De Civ. Dei x), we are said to worship those persons whom we hold in honor, so that worship and honor would seem to be the same. Therefore it is unfitting to define observance as paying worship and honor to persons in positions of dignity.

and then

Reply to Objection 1.
Worship includes not only honor, but also whatever other suitable actions are connected with the relations between man and man.

Persons of dignity, would be those who &quot;have a post&quot;. So, somewhere in there Augustine probably said that it's not right to judge a person by their post.

I hope this helps, but if you've actually read all of City of God, you'll probably know more about it than me with my perfunctory google site search of NewAdvent.org for all things Augustine that pop up on this site.