Avant garde, in a sense, can survive on its own as a kind of theory or way in which to live by. It manifests itself in the arts since art often directly reflects changes to our world and our cultures. It reflects our species' remarkable adaptation to build off the knowledge and experiences of generations, both present and ancient, to help us better understand our world. Think about all the things we wouldn't know if our parents hadn't known it first.
On the other hand, Manet, whose work has been described as avant-garde, is very famous for his work "Luncheon on the Grass". At a second glance, it makes little sense at all. It seems as though Manet is attempting to baffle his audience, to make them critically think about his work and how it may relate to realms outside of the painting. As its content was controversial and new, it challenged its viewers. People didn't know what to think of the painting and it became a scandal. It was so disliked that no one would buy it. And yet "Luncheon" is a celebrated work of art today. This is the spirit of Avant Garde. Manet is challenging his audience to think about his work and to challenge their everyday perspectives on life.