can shrug our shoulders and say, "Anything might happen; there is no way 

 of knowing". But it appears to be more profitable in every way to assume 

 that all happenings are related, that there is a connection between what 

 happens today and what happened yesterday, that the materials and forces 

 operate consistently and not erratically. We do better by depending upon 

 the consistencies which we can observe — that is, upon experience. That helps 

 us to interpret the past, as well as to plan the future. 



Everybody does probably assume that there is an order and consistency in 

 the happenings of the world. If one really believed that "anything can hap- 

 pen" without regard to what had happened before, he would be living in a 

 world that had no certainties in it whate\'er, in which you could not be sure 

 that food would ever reach your mouth or that it would do inside you today 

 what it did yesterday. The difficulty comes when we ask questions about 

 things that are not familiar; and when thinking becomes difficult, some of 

 us give up. At any rate, we do assume that in the past things happened as 

 they do now; water dissolved some substances but not others; gravity and 

 light and chemical processes acted then as they do now; gold has always been 

 heavier than iron and it has always been more resistant to acids. It is these 

 observed consistencies that give us a clue to what the world was like, probably, 

 thousands and millions of years ago — if we assume that consistency itself is 

 permanent. 



Has Life Always Existed? Year after year we may see fish hatch from 

 eggs, and oaks grow from acorns. Without examining every single fish or every 

 single oak, we say, "Life comes from life". Probably everyone has asked, 

 more or less seriously, "Which came first, the hen or the egg?'' Many reason- 

 able answers may be thinkable. We are unable, however, to test such answers 

 in a scientific way. We cannot get back to the beginnings and observe what 

 happened. Records of the past are incomplete. One of the easiest ways to 

 dispose of the hen-and-egg question is to say that there is no problem. If we 

 assume, for example, that the different kinds of plants and animals have always 

 existed, we make it unnecessary to decide which came first, or whether there 

 was ever a time when living things did not exist. 



There is something to be said for that view. When we look about us, we 

 are impressed with the constant repetition of particular events. Night follows 

 day, the seasons roll on year after year, the planets swing around the sun, 

 again and again and again. Birth, growth, death, and decay follow over and 

 over and over. When we look more closely at the materials of the world, we 

 see constant transformations in endless cycles. Every speck of water moves 

 from the clouds to the earth, from the earth to the oceans, from the oceans 

 to the air, and again into the clouds, endlessly. A particle of carbon goes from 

 the air into the solid structure of a plant, from wood to the fire. Or it goes 

 from a bit of starch in a potato into the blood of an animal, into some brain 



439 



