[The origin of life].
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EVER since he took the first steps towards a conscious life, Man has tried to solve the problems of cosmogony. The most complicated and also the most interesting of these is that of the origin of life. At different times and at different stages of culture different answers have been given. The religious teachings of all ages and peoples have usually attributed the appearance of life to some creative act by a deity. The first students of nature were very naïve in their answers to this question. Even to a man of such outstanding intelligence as Aristotle in ancient times, the idea that animals, including worms, insects and even fish, could develop from mud presented no special difficulty. On the contrary, this philosopher maintained that any dry body becoming moist or, on the other hand, any wet body becoming dry, would give rise to animals. The authority of Aristotle had an exceptionally strong influence on the outlook of men of learning in the Middle Ages. In their minds the ideas of this philosopher became interwoven with the doctrines of the fathers of the Church, often giving rise to suppositions which, to our eyes, appear stupid or even ridiculous. In the Middle Ages it was held that although the preparation of a living person, or of something like one in the form of a “homunculus”, in a retort by the mixing and distillation of various chemical substances was extremely difficult and impious, nevertheless it was undoubtedly something which could be done. The production of animals from non-living materials seemed to the scientists of those times to be so simple and ordinary that the wellknown alchemist and doctor, van Helmont, actually gave a receipt according to which it was possible to prepare mice artificially by placing damp grain and dirty rags in a covered vessel. There are a number of writings from the sixteenth and seventeenth centuries describing the transformation of water, stones and other inanimate objects into reptiles, birds and beasts. Grindel von Ach even gives a picture of frogs formed from May dew, while Aldrovandi gives drawings which show how birds and insects arise from the twigs and fruit of trees.