Standing in front of Picasso’s Guernica at Reina Sofia, I became a different person. And I don’t mean that in some cheeky, self-indulgent way. I mean it in the truest sense of the word. This change was not subtle. It was startling. I have never been a lover of modern art. With its seemingly simple brush strokes, violent streaks of color, deformed faces, stick figures, and incongruent...