The old saying that there are "two sides to every story" is not only true but deeply profound as well. It seems that everything in western civilisation is divided into two parts. To oversimplify a concept that is often grossly complex, these two "sides" can be boiled down to that which can be "seen" and that which is only "felt". In academia we refer to them as the arts and sciences; in politics, liberal and conservative. Even art itself has always had two camps. In the early 1800s, they were represented by the artists Jean Auguste Ingres on the one side and Gustave Courbet on the other. Today we might call this dichotomy abstraction versus realism.
The dominance of one or the other of these two schools of thought swings back and forth like a pendulum. It's called change and as some ancient philosopher no doubt noted, change is, ironically, the only constant in life. And, it is very nearly a definition of art. Of course that which can only be observed and that which can only be felt are both extremes. Naturally, reality (as opposed to Realism) lies somewhere in the middle. Extreme positions are always untenable. And likewise, that art which clings to either extreme, while serving the purpose of defining the limitations of what "is" or "isn't" art, is also, by its very nature, cold, empty, often ugly, and in most cases, just plain boring. The ultimate in abstract minimalism, a plain, blank canvas (arguably all black or all white), would be just as uninspiring as the most realistically painted depiction of the smallest visible detail of molecular science.
In art, nature, philosophy, politics, literature, and romance--literally any human endeavour-- some semblance of balance is needed. In art we have the Romantic landscapes of Rousseau and the observed impressions of Monet. Neither are extremes. Each however lean toward opposite polarities and both are as beautiful as they are inspiring. But perfect balance is also an extreme. Because it implies a least-common-denominator blandness, it is just as uninspiring as that art which lies at the extremes. Like a chess tourney in which every game ends in a draw, the result is not interest but ennui. If the pendulum stops, so does change, so does time, life, and art.