It appears that Benjamin Zander, who I acknowledge is a fine Mahler conductor (though not up to Bernstein), is convinced that commentaries - explanations of the music, if you will - are necessary to make complex music like the Mahler symphonies attractive to the layman. His recent Telarc releases of Mahler symphonies include companion CD's which provide his "explanations".
When I learned this, I couldn't help but recall a film I saw years ago which showed Robert Frost saying a newly written poem to a group of prep school students. When he had finished the poem, one of the kids, eager for attention, asked what the poem meant. After a short pause, Frost said the poem again from the beginning.
With all due respect to Benjamin Zander, I think Frost's response was the right one. His poetry stands on its own, and means whatever the reader or listener thinks it means and nothing more. I insist that the same is true of Mahler's music. Of course, I'm speaking as a layman.