This quote represents a smug, backwards kind of 19th century thinking that viewed history as being primarily moved by the singular actions of great men. These great men supposedly had superior intellects and characters and were just plain better than everyone else.
The quote is suggesting that you just know that the academic class is in some way, intellectually, morally or spiritually, inferior. After all, why would these men with so much knowledge end up teaching, instead of moving the world? In the 19th century, this counted as an argument.
In the 21st century, it’s still good copy, so it has survived, with whatever hateful meanings people choose to ascribe to it.