I was just speaking w/ my grad students on the role of metaphor in language & rhetoric, and it occured to us that sentence diagramming may simply be a metaphor for describing a complex concept (the hierarchy & interrelations of words in sentence) in terms of a simpler concept (visual representation of lines, diagrams, etc. found in sentence diagramming). While I stand by the assertion that diagramming can be useful, perhaps the problem w/ diagramming is that the metaphor doesn't work for many students. Metaphors only succeed w/ a group of people who can understand one concept when it is expressed in terms of a more familiar, less complex concept. One problem w/ diagramming is that it is not very familiar, and often students forget that it is nothing more than a metaphor. Hence the lack of sentence diagramming in helping students (SOME students) understand language. Thought I'd share this view while it's still fresh (but perhaps half-baked to continue that metaphor). larry beason