SECT. 2] TO THE RENAISSANCE 105 



was no better than that of St Thomas, for, agreeing with the latter 

 as Duns did that the rational soul was not an ordinary form "educed " 

 from the "potentiality" of the material, but rather an ad hoc creation 

 of God, injected by divine power into the embryo at the appropriate 

 moment, it was difficult to see how the spiritual effects of Adam's 

 fall could be transmitted to the men of each generation. It was as 

 if only acquired characteristics were inherited. But the further course 

 of theological embryology need not be pursued here ; it runs in every 

 century parallel with true scientific embryology, and it is not my 

 purpose to do more than take a glance at its progress from time to time. 

 In the Speculum Naturale, which was written about 1250, by Vincent 

 of Beauvais, the embryology of Constantine the African appears 

 again, and the embryology of Aristotle, Galen, and the scholastics 

 is to be found in Dante Alighieri (i 265-1 321), who dealt with the 

 subject in his Convivio, and especially in the Divina Commedia. In 

 Canto XXV of the Purgatorio, Statins (the personification of human 

 philosophy enlightened by divine revelation) is made to speak to 

 the poet thus: "If thy mind, my son, gives due heed to my words 

 and takes them home, they will elucidate the question thou dost ask. 

 Perfect blood which is in no case drawn from the thirsty veins, but 

 which remains behind like food that is removed from table, receives 

 in the heart informing power for all the members of the human body, 

 like the other blood which courses through the veins in order to be 

 converted into those members. After being digested a second time 

 it descends to the part whereof it is more seemly to keep silence than 

 to speak, and thence it afterwards drops into the natural receptacle 

 (the uterus) upon another's blood ; there the one blood and the other 

 mingle. One is appointed to be passive, the other to be active 

 according to the perfect place whence it proceeds (the heart). And 

 being united with it, it begins to operate, first by coagulating it, and 

 then by vivifying that to which it has given consistency, so that there 

 may be material for it to work upon [e poi avviva, Cib che per sua materia 

 fe' constare]. The active power having become a (vegetative) soul like 

 that of a plant — only differing from it in this, that the former is in 

 progress while the latter has reached its goal — thereafter works so 

 much that it moves and feels like a sea-fungus and as the next stage 

 it takes in hand to provide with organs the faculties which spring 

 from it. At this point, my son, the power which proceeds from the 

 heart of the begetter is expanded and developed, that power in which 



