How is an Urtext edition created?

Do the autograph, the first printed edition, the corrected personal copy of the composer or the revised second printing reflect the final wish of the composer? Are we dealing with different versions or pre-stages of the final form? What significance should be attached to comments made by the composer or his contemporaries in correspondence? How are we to evaluate recordings made by the composer?

Editors find themselves confronted by delicate questions of this sort in the meticulous, almost detective-like work of uncovering the “Urtext” of a work. They search for sources throughout the world, decipher almost unreadable handwriting and check for errors, contradictions and deliberate variations. The result is a reliably edited Urtext edition at the highest level.

Here are three startling examples from different Urtext editions:

Bach, Mass in B minor

Fauré, Requiem

Mussorgsky, Pictures at an Exhibition