need to know %

[This is very hard to do concisely, I appreciate your bearing with me as I try]

No! Just the opposite! If it were a matter of discrete number, the 'comparison' wouldn't work.

The contrast "contained" in the meaning of your 17C usage is ***not*** numerically expressed; the impact would be lost if it ***were***.

***IF*** I am right, and the (e.g.) 17C usage contains the trace of the word's earlier meaning, what is conveyed is simply that there is an *enormous* difference between that 10% once designated and ruin before the later (e.g,, 17C) user.

It is **not** the number change, but "viscerally" experienced change that is significant. That is to say, when "decimate," which once meant "tithe" (or other 10% taking), is applied to a ruinous event, the contrast between that more manageable original meaning and the present actual ruin is brought to the fore. The impact on understanding is not clinical, but palpable (like Hecuba's "gone all gone" -- she doesn't go around taking a numeric inventory of her losses, but wails and laments "all is gone").

This contrast is probably lost among modern users, but that doesn't mean it would not have been apparent in some way, to, e.g., 17C users (who were, perhaps, more familiar than us with the concept of tithing -- and with the sort of warfare in which one would speak of 10% dead as a kind*, and not merely as a figure of casualties*)

The encapsulated contrast is the poetry of the word and **not** its past to present ratio in number.

--As I say, this is hard to do in a couple of lines. Is that at all clearer. (and do you promise to tell me if you know anything about "amor"?)

*Incidentally, I think it would also be worth thinking about the relationship of the senses "tithing" and "war dead". The latter being a kind of "tithe to the Lord" perhaps (particularly if applied to losses during Crusades) ???

IP