There's a shortage of historic works -- Unitarian or Universalist -- on the preparation and exercise of the ministry. So -- while researching -- I was happy to see a printed set of lectures by William Phillip Tilden (1811-1890) to the Meadville Theological School, in June 1889. So we can consider these the mature words of a respected pastor.
I've not read this, but will put them on the list. Thought you might like to read it, too.