I would like to reply here to a number of criticisms concerning the stance taken by Pope John Paul II on the rights of the unborn child in his book Crossing the Threshold of Hope, made by Dr John Godfrey of the University of Edinburgh in a recent article entitled “The Pope and the Ontogeny of Persons” (Nature, 12 January, 1995).

The accusation levelled against John Paul II is contained in the subheading of John Godfrey's article: “In the recent book… Pope John Paul II airs his views on human reproduction. The pity is that he ignores most of modern genetics and embryology”. Dr Godfrey quotes the following passages written by the Pope in Crossing the Threshold of Hope: “The concept of a ‘person’ is not only a marvellous theory; it is at the centre of the human ethos… in this field more than in any other, collaboration among pastors, biologists and physicians is indispensable”.