What would be the proper usage of "Qua" in a sentence? [duplicate]

The one place where I encountered qua over and over and over was in the Random House translations of Aristotle that we used in college when studying the Greek philosophers (or more specifically, "the philosopher," as a number of medieval scholars referred to Aristotle).

A brief but not altogether enlightening explanation of qua as used in translations of Aristotle appears in the University of Washington's Introduction to Aristotle page:

Each of the special sciences studies some particular realm of being, some part of what there is. But there is also, Aristotle maintains (Metaphysics IV.1), a more general study of what there is, a study of being qua being. ('Qua' is a technical expression Aristotle uses to indicate an aspect under which something is to be considered.) The study of being qua being concerns the most general class of things, viz., everything that exists. And it studies them under their most general aspect, namely, as things that exist.

As I recall, when people asked our professor what the qua in "being qua being" meant, he said it indicated a focused interest in the thing in itself (the thing αυτος, as an ancient Greek might have expressed it)—the essence of "being as being."

However, I think that qua, unmoored from Aristotle (or Aristotle's Latin translators), loses some of the epistemological intensity of the original. Merriam-Webster's Eleventh Collegiate Dictionary (2003) has this rather lackluster entry for qua:

qua prep {L, which way, as, fr. abl. sing. fem. of qui who — more at WHO} (1647) : in the capacity or character of : AS {confusion of the role of scientist qua scientist with that of scientist as citizen—Philip Handler}

The quotation from Handler is actually the most interesting thing about this entry, because it illustrates that qua continues to be used especially in situations involving exact mirroring of a thing as itself ("scientist qua scientist") and not as often in structurally similar situations involving a thing as something else ("scientist as citizen").

My impression is that people who use qua as a fancy form of as but reserve it for reflexive a = a situations are, knowingly or not, echoing the famous "being qua being" wording from the old translations of Aristotle. In my experience, people rarely use qua as a freestanding preposition when they aren't under the spell of a philosophical investigation.

Qua (not to be confused with the ablative feminine form of qui) is a Latin adverb meaning "where; by which route". Read it as "as" when you read it. Use it in scholarly or legal writing to refer to a specific role or conceptual category for an entity that could have more than one role/conceptual category. E.g.,

All that is necessary is, that the arbiter, in the free exercise of his discretion, shall have applied his own mind, qua arbiter, to the sources of information before him...

Here "qua arbiter" modifies "his own mind" to give it the added layer of meaning "his own mind (being used for official legal reasoning, not for forming private opinions)".

Unless you are using a Latin phrase such as "sine qua non," you should not use "qua" in any English sentences. If you do, no one will know what you mean. "Sine qua non," by the way, means "the without which not." For example:

"Bork's book is the sine qua non on judicial philosophy--if you do not understand his book, you do not understand judicial philosophy."