I find when reading, that I often can’t tell why a verb should be middle instead of active, or vice-versa. I’ve read the Smyth sections on this, but is there a longer treatment somewhere, with more examples?
This has been discussed ad nauseam. Carl Conrad has published several recensions of his views on the subject.
google: middle-passive self-affected “Carl Conrad”
site:www.ibiblio.org “middle-passive” “self-affected”
site:www.ibiblio.org “middle passive”
site:www.ibiblio.org “middle-passive” Conrad
You may be interested to read Debrunner’s (1950) discussion. The chapter Genus uerbi runs through pages 217—242, and particularly the pages 222/225—236 will deal with this issue.
I don’t have it, but Rijksbaron (2006) undoubtedly discusses the question. Some commentators may be able to confirm.
The short answer: Sometimes it makes hardly any difference, sometimes it makes a lot.
And be aware that passives are sometimes used as middles (and vice versa) in tenses in which middle and passive forms are distinct (aor., fut.) as well as those in which they coincide.
I’ve looked up Rijksbaron, and it’s actually a very interesting discussion, approaching things from a non-traditional angle: goal, agent, complement, etc.
I had been thinking of purchasing Debrunner/Schwyzer at some point. Maybe now is the time. More importantly, I need to make an investment in my German to be able to read it fluently.
While I’m reading, I suppose I can be more careful about noting middle/passive forms that are not being used passively.