There was a symposium about the moratorium on recombinant DNA research. Someone said that the research would start up again, that it had to. Hans Jonas asked the simple question — "why?". A scientist answered that if we did not do it, someone else would. Therefore we had to. Again Hans Jonas asked "why?". Others may move you to examine your dearest unquestioned assumptions by the persuasiveness and complexity of their reasoning; but such is the force of Hans Jonas' intellect and moral authority that his simple question —"why?" can be more provoking of reflection and inner questioning than longer and more complicated arguments. Certainly, he has had this effect on me and this essay is a small acknowledgement of what I have learned from him. I would not think as I do were it not for him.