The water runs uphill, drops back down, spins a wheel, and runs right back up hill again. For perspective-bending artist M.C. Escher, that vision this carefully sketched lithograph.

Watch Escher's Impossible Perpetual Motion Waterfall Brought To LifeS

For YouTuber user mcwolles, it means this real life optical illusion that's giving me my biggest headache since New Year's Day. [Metafilter via The Daily What]