What did we breath before oxygen?

Flicking throught TV on Sunday morning I found CH4's T4 presenter Steven Jones telling us that Priesley was the chemist who discovered oxygen followed by Jameela explaining that we could still breath and had oxygen before it was discovered...

...small but deep point...

What did we breath before oxygen was discovered? It can't have been "oxygen" because it wasn't discovered. Indeed I don't even think that respiration was at all appreciated and certainly not oxidation in the Kreb's cycle. People would have known that we needed air to breath and that air was needed for fire and probably had an idea that the two were related... I'm too short of time to catch up on 18th century science today...

Well the answer is NULL which was true then and is true today. How we mentally construct our ideas around the evidence gives us our "image" of reality - that is a creative piece of work that occurs in history and evolves. But, the "reality" itself is NULL.

What does something look like when you are not looking at it? This is another identical question with an answer of NULL. Nothing really is everywhere!