Style in Singing

Why do great artists always make the same effect and produce the same impression on their public? Why, for instance, did the late Mme. Tietjens, when singing the following passage in Handel's Messiah, always begin with very little voice of a dulled quality, and gradually brighten its character as well as augment its volume until she reached the high G-[sharp] which is the culmination, not only of the musical phrase, but also of the tremendous announcement to which it is allied? This music instruction guide addresses these and other questions.