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Nothing against woodwinds or strings, but they're not appropriate instruments for Mass.
Brass, percussion (includes piano), strings (yes, violins and harps), and even electronincs like synthesizers, are all profane instruments.
The preferred instrument is the human voice, and secondarily there is the pipe organ.
Organ can accompany the voice(s), but for most Mass music, the voice should be a cappella. The term, "a cappella," is the standard term for voice without any instrumental accompaniment, but most instructively, it literally means, "in the manner of the chapel," because the human voice alone, without any organ or other instrument is what the manner of the chapel is, and has been since the earliest Catholic Church. In the catacombs, Chant was sung, without instrumental parts played, and the tradition grew from there. All the monasteries of renown have had daily chanting without any organ droning in the background. Gregorian Chant is always appropriately sung WITHOUT any organ.
If anyone has an objection that the voices don't stay in tune without the organ, there are two proofs of the fallacy of that claim:
1) The singers stay in tune when they learn how to make the appropriate TONE QUALITY that is just right for Mass. E.g., if a singer sounds like 'this is an opera' the tone quality is WRONG for Mass. The music sung at Mass is not a performance for entertainment.
2) When you listen to a recording of one or more voices singing Gregorian Chant with an organ accompaniment, and the singer and/or producer believe(s) that the organ keeps the singer(s) in tune, listen for pitches carefully, and you will always find that the singer with the problem is constantly a shade flat, lower than the organ, which is an ugly sound ALL THE TIME, so the organ isn't doing anything useful but merely provides ongoing DISSONANCE. This problem is generally also a problem of a tin ear in the singer, who can't tell that he is singing flat compared to the organ. In such cases, they may believe that the organ is 'necessary' otherwise the singer would just keep sinking like a leaky boat, but in fact, the singer is at BEST in a non-stop process of 'catching up to the organ' because the organ is always SHARP in comparison. So the problem is in the singer, not the organ.
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