Before we knew the three-dimensional structure of DNA, people didn’t realise it was a two chain structure to begin with. The key aspect of the structure was the complementary nature of the bases so if you had one particular of these four possible bases, if you had a big one on this side you had to have a particular small one on this side or vice versa and so on all the way up. So it meant that you could easily make, by separating the two chains, you could then easily make a new complementary copy by just obeying these pairing rules of which one went with what. And that solved in one blow the whole idea of how you replicate a gene. It didn’t prove it, of course, it merely made it a plausible hypothesis but it's turned out to be correct. And not only that but all the techniques which are nowadays used for manipulating DNA, or many of them, depend on this recognition process so you can get two things coming- two separate chains or mixtures of them and the appropriate pairs will fiddle around and come together so you can- you can select out ones you want and do all sorts of tricks. But- so the basic reason was that it showed the molecular- what was probably to be the molecular structure of the gene, it suggested how it replicated and you could read into it how the actual gene acted or many of the genes acted although that was, again, a much more speculative hypothesis which took quite a number of years to prove but turned out again to be broadly correct. Of course, because of the complicated nature of evolution, there are a lot of exceptions to these - small exceptions - to these rules but the broad picture was roughly as we saw it in those days, in those early days and it is very unusual for a static structure, just a molecular structure to give such insight into all these different- into even one function let alone a whole lot of different functions and such key functions because they are the key functions of biology. So that is why- that’s why, essentially, it is regarded as an important discovery because it complimented the original ideas of Darwin on evolution by natural selection plus genetics which was started with Mendel which showed that- that the genes were particulate and not blending and then it showed what the molecular basis was, showed how the genes act and in the last ten or fifteen years has given us a whole lot of new tools for fishing out genes, altering genes and so on which have got immense practical importance as well as being important theoretically.