As much as we value richness and variety, we also love to see a child pursue his passion for a particular medium, working with it over and over, for a whole morning or every morning for years as he unlocks its secrets, deepening both his mastery and joy in the process. When we see Abby at age two, water-coloring page after page, we trust her instinct to go deeply into that language, and relish the anticipation of what her relationship with paint might mean to her in another year or two. When Ian builds tower after tower, we observe, document, and consider what other tower-making materials we could introduce to honor his passion. When Elliot, barely three, works himself to the point of exhaustion figuring out how to reach the monkey bars, we don’t urge him to move on to other activities; we just admire his calluses and remind him to fuel up on snack when he pauses to catch his breath.  And when Jesse shifts his focus from the volatile and mighty Incredible Hulk to the wise and gentle Yoda, we are thrilled to see him represent this new passion day after day in many media.