at the end of the seventeenth century, in particular 

 Malebranche and Leibnitz, interpreted the theory of 

 preformation and the idea of "enclosing." Nicolas de 

 Malebranche, as seen in his main work, "Search for Truth," 

 did not see any improbability in the idea of the eternally 

 great number of embryos wrapped within each other. (11) 

 Malebranche, however, cannot be related to the contemporary 

 preformationists, since he took for granted the changes which 

 originate in the fetus under influences felt by the mother 

 during pregnancy. (12) From Malebranche' s example it can 

 be seen that the doctrine of "enclosing" did not necessarily 

 connect the thinkers of the seventeenth century with the 

 complete theory of preformation, but more often the two were 

 nonetheless connected. 



Preformism lies at the base of Leibnitz's opinions. 

 Leibnitz imagined that the existence of the individual 

 substances and bodies of nature proceed from the assumption 

 about the substantial forms or monads, from which is realized 

 the idea of unity of contents and form, material and power, 

 body and soul . The acting powers of nature or monads are 

 primordial and indestructible. From this comes the conclusion 

 that life is also primordial, and therefore there is no 

 basis for supposing that any dead body can become living. 

 Leibnitz decidedly objected to the assumption of spontaneous 

 generation. (13) The impossibility of spontaneous generation 

 and the preexistence of the formed organism nearly led Leibnitz 

 to the idea of the "enclosing." (14) According to Leibnitz, 

 the beginning and the end of the individual do not exist; the 

 origin of the organism consists of extension and development 

 of the preexisting organs, and death is rolling up of the 

 individuality. Leibnitz's understanding of development 

 (evolutio) was not historical (change in time), but rational, 

 i.e. a doctrine about the succession of ideas. 



Biology of the eighteenth century adopted Leibnitz's 

 idea, which was equal to his other proposition known as the 

 law of continuity of natural phenomena. The biologist- 

 Leibnitzians used the idea of continuity for the foundation 

 of their doctrine of "the chain of being." The internal 

 connection between the idea of preformation and the idea of 

 a continuity of bodies of nature, resulting from Leibnitz's 

 general philosophical conceptions (15), sometimes was kept 



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