Reductionism. That is a much later one which said… although there were reductionists already among the ancient thinkers, which said that we can get a real compete explanation of the phenomena of nature only if every more complex system is dissected into its components and then these components dissected into their components until we are down to, as they called it, to the smallest parts. Now, it turns out that this is very often confused with another methodology of science which is that of analysis. Of course, from… as… beginning with the Ionian philosophers who analyzed the world into water and fire and earth and air, all through the life of science… of science there has been analysis and analysis invariably has added to our understanding, to our knowledge. The human body was dissected into the muscles and bones and nerves and blood vessels of which it consists and that added greatly to our knowledge. There is one great difference between analysis and reduction. The person who does analysis does not claim that he has totally explained everything because he has the components but he does not have the connections between the component. If, for instance, he analyzes water and finds that it consists of hydrogen gas and oxygen gas, he can, if he is careful enough, mix these two gases and have now a gas that's mixed hydrogen and oxygen, but it still isn't water because the particular connection… the particular tying together of… hydrogen and oxygen that accounts for water has not been explained by the process of analysis. The reductionist, by contrast, says that at every lower step he has the total explanation of the preceding system, and as it is said in a simple saying, that the… the reductionist says any system is the sum of its parts, and the person does analysis says, if lucky yes, this might be the case, but very often there is more there than the sum of the parts. And I remember that I… because there is a phenomenon, which is… has been called emergence, at higher levels of putting things together almost invariably new properties, new characteristics turn up which could not have been predicted from the lower levels of the components. But this again is a… something that is explained in… in great detail in my new book This Is Biology and emergence in… even 50 years ago was considered some very soft or fishy or… or unscientific subject. And I remember in 1951 I gave a lecture in Copenhagen to a group of professors at the university and… and leading citizens, they had sort of a club together, and I… at that time I realized that emergence was highly unpopular and considered quite unscientific and I sent in my lecture which was devoted to the difference between biology and physics. I said that one of the differences between the two fields was that in biology we accept emergence and physics they don't. And lo and behold, in the audience was Niels Bohr, the famous physicist, and he got up and he said, ‘Professor Mayr, I'm afraid I must disagree with what you have said about emergence’. Well, that's exactly what I’d expected, I mean, he would say… but much to my great surprise he said, ‘You are all wrong saying that's a… that this is a difference between biology and physics because in… emergence is very widespread in… in the physical world also’. And then he quoted the example of water, and of course now, for instance, Popper has written a major paper on the subject in which he totally endorses emergence and says it is very widespread and any… almost any complex system, any higher level system has always characteristics which could not have been predicted from the components. So the rejection of reductionist… the reductionist claimed if I have all the pieces I can explain everything and build up any system. They cannot, and that is now being more and more realized. Of course, analysis is a very appropriate system, but when you make analysis you still may not know like when you analyze water into hydrogen and oxygen, you may still not yet know what interaction there is between these components.