I conducted a non-scientific poll of some of the priests I know, and they were evenly divided on which homily they dreaded most: preaching on the Trinity or preaching about money. One of them recommended to me that I start working on a Trinity homily now, because he would be very happy to let me handle preaching duties on Trinity Sunday after ordination, and suggested that Trinity was just the sort of thing that deacons should preach on. I think he may have had ulterior motives. Another one of them sent me the classic “est/non est” triangle diagram, and told me that it really got to the heart of the matter.
I still haven’t heard back from him about what it says, so I’ll see if I can make any sense of it in the next day or so.