lO THEORIES OF SPONTANEOUS GENERATION 



and clerics seized upon that which was dead in Aristotle 

 and not upon that which was alive " }'' This teaching was 

 widely accepted by theologians in the Middle Ages, especially 

 insofar as it concerned the origin of life. They held that the 

 animation of lifeless matter by the ' eternal divine spirit ' 

 constituted the essence of it. 



As an example one may here quote from one of the greatest 

 exponents of scholastic Aristotelianism, the Dominican Albert 

 von Bollstadt, known as Albertus Magnus (1193-1280). 

 According to tradition, Albertus Magnus took a gieat interest 

 in zoology, botany, alchemy and mineralogy. But in his 

 numerous works he assigns considerably less place to indepen- 

 dent observations than to material borrowed by him from 

 ancient authors. On the question of the origin of life Albertus 

 Magnus consistently supported the theory of spontaneous 

 generation, and in his book De mineralihus he specially 

 emphasised the fact that the origin of living things in the 

 presence of decay occurs as a result of the ' animating force ' 

 {virtus vivificativa) of the stars. 



In his writing on zoology Albertus Magnus gives many 

 accounts of the spontaneous generation of insects, worms, 

 eels, mice, etc., from various sorts of decaying materials, from 

 moist earth, vapours, sweat and various forms of filth. In 

 just the same way vapours of the earth and water give rise, 

 under the influence of warmth and the light of the stars, to 

 numerous plants, not only fungi but even to herbs, bushes 

 and trees which often grow in places where their seed cannot 

 have been carried.^* 



The pupil of Albertus Magnus, Thomas Aquinas (1225- 

 1274)^® also held such opinions. In his chief work, Summa 

 Theologica, he deals with questions concerning the origin 

 of life. In doing so he relies partly on the views which he 

 ascribed to Aristotle and partly on the teachings of Augustine 

 about the ' anima vegetativa '. He thus freely accepted the 

 possibility of the spontaneous generation of such animals as, 

 for example, worms, frogs and snakes as an effect of the 

 warmth of the sun in the presence of decay. Even those 

 worms which torment sinners in the infernal regions arise, 

 according to the opinion of Thomas Aquinas, in this way 

 from the rotting of their sins. In general Thomas believed 



