Harvey's epigenesis, more mechanistic and less vitalist than the Aristotelian version, was, thus, more compatible with the natural philosophy of the time. Still, the idea that unorganized matter could ultimately self-organize into life challenged the mechanistic framework of Cartesianism, which had become dominant in the Scientific Revolution. Because of technological limitations, there was no available mechanical explanation for epigenesis. It was simpler and more convenient to postulate preformed miniature organisms that expanded in accordance with mechanical laws. So convincing was this explanation that some naturalists claimed to actually see miniature preformed animals (animalcules) in eggs and miniature plants in seeds. In the case of humans, the term homunculus was used.