Forget being a unicorn. Learn to be a phoenix. Your company can last 100+ years — but you’ll need the resilience to rise and fall, and rise again. Fiat’s chair John Elkann shares the principles that helped the “horseless carriage” company founded by his great-grandfather survive the ups and downs of a century of business. One key: Resilience. Another: Deciding which company traditions to keep, and which to leave in the past.