Design Always Repeats Itself: Beware of the Dog Edition

Have you ever thought about the entomology of the term and signs that warn 'Beware of the Dog?' I sure hadn't.

I came across this today:

Cave Canem

From the House of the Tragic Poet in Pompeii. This floor mosaic reads 'Cave Canem' which is Latin for 'Beware of the Dog.'

Pompeii was covered when Mount Vesuvius erupted in 79 AD which means the term Beware of the Dog is from before then. 

Amazing. Amazing. Amazing. I am just sitting and thinking about how we still use this term today casually scrawled on signs in front yards and yet it's been around for 2000 years. 

Thoughts?

-Grace