Observations on the History of Oil Painting

I can speculate (as I often do) as to the evolution of Oil Painting; however I cannot give a definitive explanation. I am neither smart enough, nor read enough to be able to complete so complex a task. Based upon my rather limited knowledge of the source material, I can extrapolate that Oil Painting has gone from specificity, to ambiguity. Back in the Renaissance period, most paintings were very vivid depictions of people and landscapes. A few hundred years later, Monet introduced the world to impressionism, a revolutionary method of painting that was far more reliant on emotion than realism. This paved the way for the modern abstract movement, from Jackson Pollock to Robert Rauschenberg whose paintings are almost entirely emotion driven.