It is a pleasure and a privilege to introduce Norman Ford's book. When I was chairman of the Committee of Enquiry on Human Fertilisation and Embryology, which reported in 1984, I tried hard to deter members of the Committee from asking the question When does Life Begin?. I thought it an ambiguous and misleading question. The answers to it could be unhelpfully various. Eggs, sperm, even individual cells, could all be said to be human and alive. As I saw it, we had to concentrate on the question when human life becomes morally and legally important. When do we have to ensure that human embryos are given the full protection of the law? At what stage in the development of the embryo should it be a criminal offence to use it for purposes of research? These were the pragmatic questions we tried to answer, in order to give advice to future legislators.

Norman Ford, in contrast, insists on raising the question when does an individual human being come into existence. He is interested in, and learned about, the old enigma of ‘ensoulment’. But he is determined that the answers to such questions must be based on knowledge. He therefore examines the development of the human embryo immediately after fertilisation, using the knowledge that embryology now gives us.

As long as there is a possibility of two embryos, or none, developing from the loose conglomeration of cells that forms from the fertilised egg, he is not prepared to regard this conglomeration as a single entity.