It's no secret that one of the hardest things about writing and preaching and teaching is the work of narrowing - bringing one thing into focus. Read one Faulkner sentence or listen to one of Bernard's homilies and witness this work at its best.
Plowing through this week's passage or creating a new world via a short story, the author makes decisions about what stays and what goes. The sharpening process tends to be painful, for it usually means rejecting various good ideas/themes in order to focus on one matter. Hence, a shovel is no good for digging a post-hole. To achieve proper depth without disturbing a large area of soil/rock around the post, post-hole diggers fit the bill (or tractor borne augers if you're lucky).
I hope to preach the gospel clearly and well, which requires sound and thorough learning - a willingness to contently dig in one place for a while. I have to remember that there's always next week or next time (next article for you scholars), so it's ok and even necessary to reject a handful of good things in preparation. After all, when it comes to writing and teaching in the Church, in the words of Robert Earl Keen, "the road goes on forever and the party never ends."