There are a lot of complexities when you say, “How did the first DNA molecules come about?” Now we realize it must have started with RNA. You can ask, “Did it start with RNA as we know it today?” Can you really guess what the chemical events were three or four billion years ago? The answer is no, we can’t right now. So we can’t really prove we know how life came about. But when you saw DNA, you at least knew how life as it exists now is made possible. Of course, since finding the double helix, we’ve discovered an enormous amount of things which make the picture more and more complete. But it was the breakthrough we needed to get on the right track.