Dear Dr. Boli: Why is the symbol of Ireland a shamrock? —Sincerely, Col. Seamus O’Mack (retired).

Dear Sir: When, in 1922, the Irish Free State was formed, it was weakened by decades of struggle for independence and a current civil war. Economic conditions were dismal, and what money the weak central government possessed could not be wasted on useless luxuries. In short, Ireland was too poor to afford a real rock, so  a false one was hastily substituted. Since then, of course, Ireland, the “Celtic Tiger,” has prospered, and indeed has become renowned for the number and quality of its rocks. But the memory of those difficult days persists, and the shamrock remains as a tribute to the struggles of the founders of the Irish nation.