Is the idea of “brand” constant or evolving?

I came across this charming ad from Coca-Cola. It’s from 1890. It’s obviously from another era, but the intent behind the brand is the same — Coke is trying to evoke an emotion of youthful vigor and sophistication … all at a good price.

Some things never change, but mostly they do. I’ve been thinking a lot about this lately. How has the idea of “brand” evolved over the decades?