As Christianity spread, what had once been a pagan festival became more a tradition to keep all that was pagan at bay. The fires were lit to ward off witches and part of this process included burning old broom sticks. Today, the night is more an opportunity to get together with friends to build a fire and enjoy the outdoors, which hopefully are by now warmer and with all the vestiges of winter gone. The origins of the day will give you something to talk about while enjoying a beer and roasting buřty (fat Czech sausages) over an open fire.