A Latourian conundrum, please help.

"Existence precedes essence". Bruno Latour (1993)
from Latour, B. (1993). Pasteur on lactic acid yeast: A partial semiotic analysis. Configurations, 1(1), 129-146.

However, isn't this a chicken and egg dilemma?
i think therefore I am, I am therefore I think.
Or crudely, I think and then I do.... I do and then I think, whats preceding?
Isn't there's always a before?
I get that things get shaped iteratively, for example:
I can do counselling, and in the performance their is an essence, or several essences; belonging, being in the moment...empathy. They dont exist outside of performance, but htey are aspired to and recognised as valuable in a therapeutic interaction...and therefore they are taught and aspired to...seems to me ts an 'and and' issue.

To adapt some Latourian critique of Pasteur and turn it on Latour himself:
Is Latour not giving his entity a little nudge forward? ...He is doing the action, he has prejudices, he is filling the gap?
Are not the metalinguistic resources that I apply handed to me directly by the author...

Well yes, and it leaves me stuck. I think there's a middle ground here that could be better explored. Latour (2005) in Reassembling the social, suggests its always best to start in the middle and maybe I have taken this literally, that there is always a middle? And therefore the apparent inconsistency of existence preceding essence.

However, Latour (1993) also admonishes:
"As long as we have not understood why what appears to us as a contradiction is not one for Pasteur (read Latour), we do not learn from those we study--we simply impose our philosophical categories upon their work."

And so i stay stuck, I feel like I am in a mobius strip.
So I have some uncertainty here, and I'd truly like it discussed. Please help me with this, its interfering with my sleep and my study.

BTW I found my folder :)