Why do we still ask people to mark an X? Like many things, we trace the root back to Rome. The notarial subscriptio solved a pretty simple problem: how do you prove a document is genuine, and that the person named on it actually agreed to it, in a world with no photo ID and no database to check against? Rome's answer was to have each person add their own line in their own hand, underneath the document. A judge might write something like "I, callum, have subscribed," and witne