The title of Volume 52 of the new English version of the Summa Tkeologiae, ‘The Childhood of Christ’, could be misleading if it suggested a biographical work. As Fr Potter remarks it is ‘essentially a theological treatment of some Gospel events’, and these are predominantly pre-natal, though they include Christ’s manifestation to the shepherds and the magi and his circumcision. St Thomas is concerned, in most of this treatise, to bring together two realms of thought of very different importance and authority, namely orthodox Chalcedonian Christology and the accepted genetics and embryology of his time. The latter have, of course, been completely superseded by later biological research, and the reader is therefore repeatedly confronted with the question of the manner and degree in which St Thomas’s arguments need revision and reassessment, though this has little bearing on the strictly theological, or at any rate on the strictly dogmatic, aspects of the matter. Fr Potter devotes a little space to these considerations in his appendix on ‘Jesus in his mother’s womb’; one might have wished for more, even at the expense of inflating the volume and its price. It is, in fact, remarkable how little attention seems to have been paid by theologians to the embryological and obstetric aspects of the Incarnation in recent years; medieval theologians did not feel that reverence necessitated this kind of reticence. The only modern work that I know on the subject is The Mother of God: Her Physical Maternity, a reappraisal (River Forest, 111., 1964) by Fr Cletus Wessels, O.P., though A.