"An High Priest of Good Things to Come" -- why "An"?

Question

I am watching a video of one of the Apostles of the Mormon Church, Elder Holland, which is entitled:

"An High Priest of Good Things to Come"

The video contains this line:

"Speaking of Jesus’ “more excellent ministry” and why He is “the mediator of a better covenant” filled with “better promises,” this author—presumably the Apostle Paul—tells us that through His mediation and Atonement, Christ became “an high priest of good things to come.”"

Can anyone tell me why he is using the phrase "an high priest" instead of the more conventional "a high priest"? Although the text is a translation from the original language, the address was a mass address intended for members of the general laity, rather than purely biblical scholars. Thus it seems that the a is likely to have been deliberately left in, in order to evoke some sense of the word an to an English speaking audience which is not present in the word a, and therefore retain more of the intentionality of the original text...

Could anyone offer an explanation as to what an is doing in this text, in an English Language sense, which a would not have been appropriate for, or would in some way have been detrimental to the message of (or could be considered to be detrimental to the message of)?

Statement of Non-Duplicate Status

I'm after a specific answer for this passage, not just general rules for an and a. I would also like something a little more than "it sounds nicer", which isn't really an answer; preferably something which broaches any subtle differences in meaning between the two words, and the manner in which the sense of passage would be different if it were to utilise a instead of an.

(Link to video for reference: https://www.lds.org/general-conference/1999/10/an-high-priest-of-good-things-to-come?lang=eng)

Answer 1

The wording of “an high priest” is archaic, and this creates a feeling of separation from ordinary language that you don't get as much with "a high priest."

Peter Shor pointed out in a comment that “an high priest” is a quote from the King James Bible, one of the most influential Christian texts in English. The King James Bible apparently uses “an” before many words that start with an “h” where we would use “a” in modern speech.

The use of“an” before words like “high” that start with a pronounced “h” followed by a stressed vowel should be distinguished from the use of “an” before words like “historical” which start with a pronounced “h” followed by an unstressed vowel. Some people still use “an historical” today in ordinary registers of speech, but I know of nobody who would use “an high” outside of religious or otherwise archaic language (setting aside people who drop the "h" in "high").

Answer 2

My impulse is to attribute it to two conventions: first, to a longer-standing custom of using a construct like "an historian" from British english — I encountered this constantly when reading Daniel Defoe's writings from..dunno, it was somewhere like the 18th century (somewhere 1500-1800..clearly not a historian).

Second, the inclusion of "an", particularly within a writing that isn't all that old (the Mormon version, which draws on clearly much-older and historically-evolving sources) and which is firmly rooted in American tradition, seems to me primarily to serve an oratorial purpose with a mild grandiosity — i.e., it just doesn't sound as ordinary as a grocery list or a periodical's articles.

So as to your broader question about the "an" modifying the larger message of the passage, I don't suspect it plays any other than a small reinforcing role in concert with the rest to collectively amplify the message that Jesus' personal growth in those matters far-surpassed mortal challenges — which, even so, were particularly fraught with travail, suffering, and death — by having to surmount existential challenges that could best the best among us, but then He also had to find His own spiritual path (on which the laity could never hope to follow) as He opened and navigated a nearly inconceivable bridge between mortality and divinity, to the betterment of all.

In short, I'd say it just serves to help impress upon all recipients of the message that this was anything but a normal undertaking which resulted in a theretofore-unparalleled moral ascension along His way to even more.