I can't work out the Celts.
Are they an echo of a Europe that was ready to go only so far in its submission to logic and rationality? A race that holds on to some important, though perhaps unwritten, insights into life and the Universe? Brave and wild tribes that would rather proudly fight to death that unite and win? Or simply noisy and poorly-disorganized - but not without some charm - peoples* that just unruly waited for the Romans or, locally, a French-speaking contingent of former Vikings to conquer them?
(Then perhaps, frustratingly, a mixture of all of them?)
*quite like some Slavs