In his Dec. 12 letter, it’s Ken Marks’ knowledge of history that needs a refresher course. The Constitution is silent on the issue of state secession, because it’s never been a question of “legality or illegality,” it’s because it’s a complete nonsequitur. It’s simply not possible for any state to secede from the Union. The Union is inviolable. While the underlying cause of the Civil War was certainly the South’s desire to perpetuate slavery, the proximate cause was simply that Southern states began to secede. Lincoln’s (correct) assertion was they could not, hence their army was no different than any other armed band in rebellion. The Civil War settled this issue, and it’s time for Texas and the South to get over it!