Leonardo DaVinci noted that when trees branch, smaller branches have a precise, mathematical relationship to the branch they sprang from. iStockphoto.com hide caption

toggle caption iStockphoto.com

Dr. Alfredo Quiñones-Hinojosa picked tomatoes, shoveled sulfur and scraped fish lard before becoming one of America's most respected neurosurgeons. Keith Weller hide caption

toggle caption Keith Weller

NPR thanks our sponsors

Become an NPR sponsor