On the Hymn of the Day
In Lutheran history, three terms have been roughly synonymous: Gradual Hymn (Graduallied), Chief Hymn (Hauptlied), and Hymn of the Day (De Tempore, lit. belonging to the time). Many early missals omit the Gradual chants; instead, chorales were assigned to be sung at that place. As the corpus of Lutheran hymnody increased, many hymns became strongly associated with particular Sundays. Some were old Latin office hymns that moved naturally into the Sunday mass (e.g. "Savior of the Nations, Come," the adaptation of veni redemptor gentium); others fit particularly well with the themes of the day (e.g. "A Mighty Fortress" on Invocavit, the first Sunday in Lent, where Christ "is by our side upon the plain" battling Satan for us) or the season. Not all Sundays of the Church Year have a definitive hymn belonging to that day.
The term "Chief Hymn" highlights the importance of the hymn not only among the propers of the day, but also in the life and usage of the Lutheran confession and suggests that priority be given to those hymns common to the catholic heritage (pre-Reformation hymns in common use in the western Church) and those arising from the pure teaching of the Augsburg Confession (i.e., composed by Lutherans since)The term "Hymn of the Day" highlights that it has earned a place among the propers of the day. This means that it stands as one star in the constellation of Scriptures, prayers, and Psalm selections for that service. All of the texts and purposes of the day itself have contributed to the choosing of that hymn. In recent years, many Lutherans are familiar with Hymn of the Day lists found in the back of their hymnal or in other resources like the LSB Hymn Selection guide. These lists, drafted by worship committees, usually reflect historic associations and priorities, though they are often willing to include hymns from other protestant traditions also.
The term "Gradual Hymn" has fallen out of use especially through the use of the common service, which has restored the use of intervenient chants (with some success), and this is fine. Lutherans are now familiar with the pattern of Gospel, Creed, Hymn of the Day, Sermon. This is a fine progression that allows the Prophets (Old Testament), Apostles (Epistle), and Christ Himself (Gospel) to preach first. The whole Church confesses and echoes this truth (the Creed), and the poets of the Church are also allowed to comment (the Hymn). Only then does the pastor dare to preach (and indeed, what he says will sound quite hollow if it contradicts all the greater lights who have "weighed in" already).
This placement, however, has created a side effect: that the Hymn of the Day is sometimes treated instead as "the Sermon Hymn." Rather than a hymn proper to the entire day (having some connection and place among all the other propers), it becomes a hymn chosen for the occasion. It may be chosen (ideally) because it matches with the Scripture on which the sermon is preached; it may also be chosen because it matches what the pastor expects to say (perhaps regardless of any text). There is a sense among most preachers and even more laity that the sermon is the pastor's purview. However, when the Hymn of the Day becomes the "Sermon Hymn," it also becomes the pastor's purview. Perhaps the sermon hymn is really the Pastor's Hymn.
This understanding of the Hymn of the Day as a Sermon Hymn should be avoided. Most pastors (rightly) have immense freedom to exercise their judgment over the other hymns used in the service. The high Office they hold must be sufficient to keep them from abusing that authority by choosing the favorites (theirs or the congregation's) only; application of the propers for the purpose of instructing and comforting Christian consciences is rather the chief guide in hymn selection. When it comes to the Hymn of the Day, however, this should be treated as a true proper, as its name suggests. It is the chief hymn appointed for the day. The Church at large, for the most part, has determined that this hymn is worth our time and applies to our consciences today. The benefit of following this advice is that your people will associate these beloved Scriptures and doctrines also with these hymns.
How does a pastor with any musicians work toward this proper appreciation of the Hymn of the Day? Here are my suggestions:
1. Choose your list and plan on sticking to it. Pastors who have looked into the Hymns of the Day know where traditions have diverged. Since it is the newest of the propers (other than the restored Old Testament), it is the least settled. Every new hymn committee weighs in, along with many other wise voices. Far be it from me to exclude your study from that also. In my judgment, "Praise the One who Breaks the Darkness" can't rise to the level of "Haupt" to stand next to the other chorales associated with the 14th Sunday after Trinity. I would substitute "From God shall Nothing Move Me." Perhaps you prefer, "My Soul, Now Praise Thy Maker." (Both have some pedigree.) You may begin with one and be convinced of another some other day, and there is always the chance that a truly worthy hymn supplants them both by large consensus. This is a fine example of a true adiaphoron, a difference in ceremonies that isn't church-divisive. How will you use your freedom to highlight the principle that the Hymn of the Day is just that and not a "Sermon Hymn" of your own whim? I suggest you make a choice and stick with it. Take LSB's Hymn of the Day list as your starting point, be in conversation with the wise musicians and pastors you know, but adjust for longevity and consistency. Be disciplined to stick to it and hesitant to change from year to year.
2. What if my parish doesn't know that hymn? This is a good reason to deviate. In many parishes, the core hymns of our Lutheran confession simply haven't been sung. God help us, we're missing out! Your list may have a lot of unknowns in it, and you won't be able to teach them all immediately. You will work toward it. Having a list helps you know the direction to go. You will have to do the "sermon hymn" thing for a while on some days. Again, the desire for consistency will help you. For example, my own parish does not know Luther's "Christ Jesus Lay in Death's Strong Bands," the undisputed Hymn of the Day for Easter. We sing "Awake, My Heart, With Gladness" in its place. Some day, God willing, we will learn Luther's hymn and have to sing "Awake, My Heart" somewhere else.
3. Highlight these hymns in your sermon. Just because it isn't your "Sermon Hymn" doesn't mean it can't be part of your sermon. The value of Lutheran biblical and liturgical preaching (especially with the one-year lectionary, which gives you the freedom of repetition) is that you do not have to bludgeon people over the head with the theme you fancied for this particular day. Far more than preaching a text (though the text is never far), we are freed to preach a day. This is easiest and most obvious on feasts—the event and doctrine of Transfiguration is what we preach, not just 2 Peter 1 or Matthew 17. Likewise our Hymns of the Day have depth and richness in concert with the rest of the propers. They only rarely quote or repeat the stories and texts of the day—usually on feasts.
4. Lean into the repetition and consistency. "Good Shepherd Sunday" is universal. Everyone knows it, even if they don't know when it is or which lectionary they're using. They expect it. They expect to sing certain hymns and hear certain readings. The same is true for every major feast. It's also true for that Sunday we hear Jesus say "do not be anxious," whenever that is... (it's Trinity 15). Boy, don't I need to hear the rebuke and the comfort of that truth: what God ordains is always good. That's what we should call it, shouldn't we? "What God Ordains is Always Good Sunday." With the consistent Hymns of the Day, you don't have to call it that to have the benefit of sound expectation. Sometimes a Sunday has my favorite hymn at the center; sometimes my favorite Sundays' hymns become new favorites; most of all, I am taught by frequency and pride of place that these hymns are worth my time. They get lodged deeply. And that's not because my pastor or my organist or I really chose and liked them so much; I am reaping the benefit of the Church's collective wisdom yet again.