A gentleman reigns as king of his castle, defender of his domain. Since civilization’s birth, what does any proper citadel need? A flag. Flags mark territory. They declare sovereignty or affiliation. Through symbols, shapes and colors, a flag tells a story to outsiders about the land and its people. To insiders, a flag emphasizes unifying values and shared aspirations. You may have a mortgage. You may mow the grass biweekly. You even may have replaced the kitchen backsplash. But, you do not own a house until you fly a flag on it. What flag, you ask. This is not Fifteenth-Century Scotland: you do not need a coat of arms. Instead, select the flag of an organization with which you associate, e.g., a university, the Marine Corps, or an athletic team. Or, patriotically hoist the American flag. Do not, however, fly...