"Imagine that some "barbarian" tribe had over-run part of Europe and captured a couple of grand pianos. They then use them in one of their tribal dances, with drummers beating, dancers spinning about and thrusting spears over their heads, and the pianists pounding away in time with the whole chaotic ruckus. You'll have a fair idea of the effect of Bartok's Sonata for Two Pianos and Percussion. While Stravinsky in the 1930s was well into his long "neo-classical" phase, Varese and Bartok were keeping alive the "neo-primitive" movement in their music (though each in different ways). In the last movement of the Sonata, it's as if the pianists sneak out after everyone else is asleep, and try to play some of the "delicate" European music they'd heard from their captives, though of course their version has a sort of awkwardness and energy. The whole thing is just another masterpiece from the amazing Bartok."