The working out of variations without moving the pieces physically. Though this book has taught you to talk or reason your way through a game, there are many positions that have a purely tactical nature. In such situations the player’s ability to calculate variations accurately takes on great importance. The way to train your combinative (calculative) vision is to study the games of attacking players like Alekhine, Tal or Kasparov. Follow their opening moves and then cover up the rest of the game score. At this point you should endeavor to figure out all the imbalances, the plans, candidate moves, etc. When this is done, calculate each candidate move as deeply as you can, writing down all this information as you go. All these things must be done without moving the pieces around. When you have done all that’s possible (take as much time as you need, we are looking for accuracy; speed will follow with practice), look at the move played, make it on your board and keep repeating the process until the game is complete. Keep a notebook with all your analysis. At first you may not do well, but with practice and effort you will notice real improvement in every aspect of your game.