We chose to work with SV40 because there had been a sort of significant contaminant in the first batches of the Sabin vaccine. So some 4 million Americans have been injected with SV40 and there was no immediate spike in cancer incidents. So we didn't think it was an immediate danger, but you couldn't say that it wouldn't lead to a spike of cancer 20 years later. It was one of those sort of things we knew we had to work on. Medical microbiology had had a tradition of sort of maybe the investigator dies from the disease he's investigating. And we put the lab under negative pressure so that everything would flow into the lab and not flow out. So we did about as much as we could do without really slowing down the rate at which we did experiments, but I think the community just went ahead. Under today's climate, it might not have been so easy just to say, we don't worry about whether innocent technicians will come down with it. When you can't measure risk it's hard to know - whereas the risk from cancer was high and we thought at the time that studying the viruses was the best way to get at the essence of cancer. This was before recombinant DNA, so there was no way really to go in and investigate the, whether the normal DNA contained sequences which were changed in cancer. Everything changed in 1973 when the possibility of recombinant DNA opened up and you could clone sort of big pieces of DNA. But then in a much more serious way, also a general question was raised whether recombinant DNA was dangerous. You know, could you use it to make biological warfare more efficient? Or, you know, when you're inserting into the recombinant DNA and cloning cancer genes where, you know, the possibility that this DNA in some form or other could infect the people who are working with it. So in fact, it was one of our staff members at Cold Spring Harbor who raised it, the possibility. And I think at this time we wanted to seem like good guys. And so there was a meeting at MIT, I think David, in David Baltimore's office, and we wrote out a small paragraph calling for a moratorium on recombinant DNA experiments until we had more properly thought through the question of whether health hazards should restrict the way such experiments were done. That led to, you know, a year later, a meeting in California near Monterey at a conference centre, the Somer Conference Center, where sort of 100 molecular biologists, best and brightest, assembled to discuss whether to just go ahead without regulations. To my annoyance, I found that everyone felt if we had a meeting we would disappoint the public for which this was appearing in the press if we didn't regulate it. But Joshua Lederberg, who I've never really been very fond of and sort of instinctively was sort of opposed to most things he did, he gave a very impassioned speech again regulating and I found myself totally in agreement with Joshua. And I think Stanley Cohen was against it.