Bernie Sanders inspires fervent love and, even among his enemies, a measure of grudging respect--yet, curiously, we know little about who the man really is, with Sanders deliberately keeping the focus on his policies. Now, with The Fighting Soul, Ari Rabin-Havt takes us where no profiles or televised interviews have been able to go. As a close advisor and deputy campaign manager on Sanders's most recent--and likely last--presidential campaign,...