Karl Marx’s father, Heinrich, converted from Judaism to Protestantism in 1817 – later converting his eight children – because had he not done so, he would not have been allowed to practice law in Prussia. He wasn’t alone in having to change or disguise his Judaism so that he could earn a living. There was practically no other way for Jews living in Europe in the 19th century to be part of the business class without renouncing their religion. This practice actually harkened back for eons, at least two millennia to be precise, as Jews in Europe found other ways...