A pea-souper had descended on London and it was oddly quiet in our rooms in Baker Street. Holmes mused before a roaring fire, apparently oblivious to all around him.

"Holmes, I wonder if I may venture a question on your favourite game?"

"By all means, Watson. My case load contains nothing of great moment, so what better way to spend an evening?"

"I have noticed that when I play my pace is constant. I roll the dice, study the candidate moves as you have taught me, make my selection and move my men. Yet when I watch you, I notice that you play some moves with no apparent thought, whilst others take a considerable time. You take the longest time of all when dealing with cube decisions."

"Ah, Watson," replied the great detective, "you have hit upon a key factor of successful backgammon. You cannot play like an automaton. This is a highly complex game even to someone of my intellect. It is true that there are positions where the difference in equity between two possible moves is minute. For example the play of a "1" in a bear-off. In such instances I will often move quickly and conserve my mental energy for the more difficult decisions. Playing top-class backgammon is very tiring and you should not expend energy needlessly.

"On many moves my choice may affect the type of game that will result; on others there may well be a huge equity difference between two candidates. In these situations I will take the time to apply my knowledge and techniques to make sure that I make the right choice more often than not. Even great players are said to make the best move only 80 per cent of the time and my research shows that even this estimate may be too high. As for doubling, look at it this way. In a game you may make 30 moves but you are likely to have to make no more than two doubling cube decisions. It is therefore worth investing the time to evaluate the position accurately. As I have told you before, the largest errors made when moving the men do not begin to equal the equity given away by bad cube decisions."

"Thank you, Holmes. As ever, a lucid explanation."

"Rudimentary, my dear Watson."