12 ἀρχῆς ἁπάσης ἡγεμὼν ἔστω λόγος.
Let reason be the guide of all authority.
or May all authority be guided by reason.
It might make sense to interpret ἀρχῆ as beginning here but it seems less likely.
How about understanding it based on the Greek order:
Of every commencement, the leader should be Logos.
Still, I don’t know, what is the context? Then, we can decide whether it is beginning or authority.