My answer as regards the first of these two examples is as decided a "No" as my "Yes" is in regard to the second. This may, perhaps, be considered somewhat arbitrary and entirely a matter of taste, but I venture to hope that after what I have to say on the subject it will be found to be only partly a matter of taste, and of arbitrariness not at all. I base my objection to the alteration in the first, and my approval of that in the second example on a theory which seems to me to commend itself by its simplicity, and may be explained in the shape of a rule something like this:
Take the note as to the changing of which into a higher or lower you are in doubt, and look first at the note preceding and then at the note following that doubtful note. Then see if the note you wish to substitute for the printed note lies on the way from the preceding to the following note. If it does, you are justified in making the change; if not, leave it alone. Here is our first example:
The doubtful note is the C on "shep," the preceding one is the G below, the following is the C. Now, does the D you wish to substitute for the C on "shep" lie between that "G" and that "C" on the second syllable of shepherd? No, let the phrase therefore remain as written. In the second example:
The questionable note is the A on "Da" and does lie on the way from the C sharp to the A on the second syllable of David; it is, therefore, not only perfectly legitimate, but even good to make the change, and the phrase should be sung:
The question of taste enters when it comes to the exception to the rule. According to that it would be legitimate, taking yet a third example from the Messiah:
In this case, however, it would be decidedly better to leave the phrase unchanged, for we have had four B flats already in that short sentence, and the A, coming pat on the F major chord, is rather relieving and refreshing. Here, as in many other cases, "let your own discretion be your tutor." Of an exception to the rule as regards the first of these three examples being either justifiable or advisable I know no instance. Of course, all I have said on this subject refers to the slow, deliberate, serious recitative in oratorio and other sacred music only, and not at all to what is called "secco" recitative in opera, which is practically no more than speech somewhat rapidly delivered in specified musical terms. There you should change the doubtful note into one above or below it at every opportunity, for by doing so you impart a certain spontaneity and freedom to the sentences, emphasising their resemblance to the spoken word. Here is an example in the style of Mozart: