98 INHERITANCE IN ANIMALS 



After making my first throw with both dice, I pick up 

 only the white die, letting the red pass over into the 

 second throw, exactly as it was when it affected the result 

 of the first throw. Here I make a first throw, and it 

 happens that both the dice show more than three points ; 

 the red one shows four, and the white one six. That means 

 that one of the dice I shall count in my second throw 

 will certainly show more than three points, and all my 

 uncertainty about the second result is due to my ignorance 

 of what the other will show me. I now pick up the white 

 die and toss it again, it shows two points only, so that for 

 what I call a second result I have one die with more than 

 three points, and one with less. 



Just consider for a moment how much the knowledge, 

 that one of the two elements on which the result of the 

 first throw depended will pass unchanged into the second 

 throw, has diminished my uncertainty about the result of 

 the second throw. Whenever I throw two dice, both of 

 them may show more than three points, or only one of 

 them, or neither, may do so. A simple calculation shows 

 you that if I make a long series of such throws, 

 throwing both dice every time, both the dice will show 

 more than three points about once in four trials, one of 

 them only will show more than three points twice, and 

 once in four trials both the dice will fail to show the 

 points I am looking for. But if I know that both my dice 

 showed more than three points in the first throw, and if 

 I know that one of these will pass unchanged into the 

 second throw, then I am sure that one of the two elements 

 on which my second result depends will give more than 

 three points, and my only uncertainty about the second 

 result arises from my inability to predict what the second 

 die will do. The single die I toss again to form my 

 second result will show more than three points about 



