One, and sometimes more engines, toil without rationing electricity, sometimes checking on their masters ideas or more oft en showing their own evaluations and recommendations on screen with each conclusion supplemented by an exact numeric equivalent. There is no arguing with such an expert. Is it even necessary? He, as the almighty judge, knows all and can answer any question. All that is needed is patience. During a mutual training session, a young player who is currently one of the top in the world, asked Garry Kasparov: How did you evaluate positions in the past? After all standard evaluations like better or worse are too vague and cannot begin to satisfy a modern professional. Th e very question feels like a giant gap between the approach to solving chess problems then and now. Intuition and improvisation are gradually phased out by exact knowledge and calculation. So far this has only become fully evident in the opening. More than anything else it has become opening preparation which has made the biggest fundamental change to professional chess. So now let us peer behind the curtain!