GoodFellows celebrates its 100th episode with Hoover senior fellows Niall Ferguson, H. R. McMaster, and John Cochrane reflecting on social, economic, and geopolitical lessons learned since their first conversation nearly three years ago. Also debated: the merits of the World Economic Forum in Davos, the spectacle of climate-change bloviation, plus the strategic implications of sending American heavy tanks to Ukraine (Lt. Gen. McMaster knowing a thing or two about the topic, having led armored cavalry regiments into combat).