"There is no standard concert hall repertoire in which lack of sensitivity to tempo and Expression marks is more damaging than Mahler's symphonies. Their coherence lies in a series of tonal relationships emphasized by thematic connections, and tempo provides the medium through which these connections are made. Drawing on the writings of Mahler's friend Natalie Bauer-Lechner, the importance of tempo in Mahler's works is illustrated by the composer's own words."
Raabe, Nancy M.
"Tempo in Mahler as Recollected by Natalie Bauer-Lechner,"
Performance Practice Review:
1, Article 3.
Available at: http://scholarship.claremont.edu/ppr/vol3/iss1/3