In general, the idea is to be able to see different positions in your head without touching the pieces. Of course, with computer and Internet chess, you can move the pieces on the "analysis" board to your heart's content, something you could not do over the board in a "real" game!
Players in tournaments also had a touch rule - you must move a piece if you touch it, if it has a legal move, so they had to figure things out mentally.
Hope this helps!


Is it all in your head with your hands behind your back? No board? No chessmen to move? I ask this because in "Rapid Chess Improvement" de la Maza (which I have just started reading) speaks of doing chess vision drills. He goes on about an exercise with concentric circles, then says " place your queen here..." etc. I am confused and mad and wish I had never opened this book or heard about "chess visualization." Life was hard enough with a real chess board and chessmen I could touch and move... Anyone read this book? Stwils