Who first labelled the collection of Bach's 18 Chorale Preludes for organ (BWV 651–668) as "Great" and why?

Question

Who first labelled the collection of Bach's 18 Chorale Preludes for organ (BWV 651–668) as "Great" and why?

• Is it "Great" because of the epic scale" in contrast with the "miniature intimacy of the choral preludes of the Orgelbüchlein" (trans. "little organ book")?
• Is it "Great" because (as Bach's biographer Philipp Spitta put it) represent "the very quintessence of all he elaborated in Weimar in this field of art" (i.e. the best that Bach has produced)?
• Is it "Great" because the name-giver recognized that in this collection Bach (I'm speculating here) consciously used every Chorale Prelude writing technique to the utmost?
• Is it "Great" because Bach himself designated the collection as a pedagogy for writing great chorale preludes, the way he composed The Art of Fugue?
• Is there a unity to this collection, like Bach's self-consciously group the WTC together?
• Is it known as "Great" among German musicians / musicologists as well, considering that in German Wikipedia there is no "Great" in the collection title Achtzehn Choräle von verschiedener Art?

Hints

• Various alternate names of the collection, courtesy of IMSLP (thanks @Aaron):
  • Alternative Title: Achtzehn Choräle von verschiedener Art; The Great Eighteen; Chorals de Leipzig
  • Name Translations: Great Eighteen Chorale Preludes; Leipziger koralen; Dei store atten koralpreludia; Achtzehn Choräle; Preludi corali di Lipsia; Leipzigkoraler; Divuit Grans Preludis Corals; Chorals de Leipzig; Dieciocho grandes preludios corales
  • Name Aliases: Leipziger Choräle; Choräle von verschiedener Art, BWV 651-668; Leipziger koralen (J.S. Bach); Achttien koraalvoorspelen; Choräle von verschiedener Art; Chorale von verschiedener Art; Diciotto corali di Lipsia; Atten koraler (Bach); 18 Grans Preludis Corals; BWV 651–668
• ChatGPT says that it's Phillip Spitta, in his Bach biography published in 1873 and 1880, but I don't trust its answer to the "why", which may be hallucination endemic to LLM generative AI. Plus, (typical to ChatGPT), it doesn't provide a quote and a standard footnote reference to Spitta's books.

Answer 1

First of all keep in mind that the titles of such collections are quite arbitrary and usually chosen by the editor (I’m not sure if Bach had made specifications about the title). Then attributes like great are often not included as a qualitative evaluation, but as sign of scale or importance — especially to avoid confusion with similar works (e.g. compare Schubert Symphony 6 and 8, both in C major, so the latter was termed "the great C major" to distinquish these two).

The first case of attribution of "great" to this collection I’ve found using google books search is in the 1921 publication "Bach's Chorals (III)" by Charles Sanford Terry. There the collection is usually refered to as Eighteen chorals or The “Achtzehn Choräle”, but in the beginning it says:

The Autograph of the Eighteen Chorals or Great Chorals [...]

Thus I suppose that the collection was historically simply referred to as the great chorals, using great as a means of differentiation to lesser collections of chorals or whatever.

In the following time you’d find many “Great eighteen” references, which I would rather see as a colloquialism rather than really a title.