I took a course in Old English as part of my undergrad studies. I loved it, although I don’t remember a great deal of it beyond some etymologies and a recollection of some dirty riddles.  One word I do remember is the one at the very start of Beowulf:

Hwæt wē Gār-Dena in gēar-dagum…

(The Spear-Danes in days gone by…)

I’ve deliberately avoided hwæt in the translation, because it’s given translators and scholars a bit of a headache over the centuries. It is related to our modern English what, but in this sentence initial position is often translated as ‘lo’, ‘hark’, or ‘listen’. A kind of ‘ok guys’ interjection before you launch into a story.

Seamus Heaney talks about his famous translation of the text, observing that the usual translations are a bit archaic and pompous, and noting that:

…in Hiberno-English Scullion-speak, the particle ‘so’ came naturally to the rescue, because in that idiom ‘so’ operates as an expression that obliterates all previous discourse and narrative, and at the same time functions as an exclamation calling for immediate attention.

Not everyone agrees with this, and some have argued that it is not an interjection at all, but just a way to begin a sentence.

Even with the issue of translation aside, hwæt is interesting because it’s only in recent generations that English speakers have completely moved from saying /hwæt/ to something more like /wɒt/ or /wʌt/ without the initial /h/. That little breath of air was the last phonological reminder of the Proto-Indo-European *kʷ cluster that links English wh- question words like what and which to those in other European languages like Latin quī (‘which’), French qui (‘which’) and Spanish cuando (‘when’).