Here’s some descriptions of P/E (yes, from Wikipedia) and some wonderful pictures. The best way to learn is to look at the artists’ work after Manet – preferably at a museum. I saw several Monets, Van Goghs, Cezannes and Gauguins recently. In person, you can see the techniques, brush strokes, colours, subject matter and general impression or post-impression. The terms are not cut in stone (or am I talking about sculpture now).