The present study attempts to lay the basis for a sound approach to the uniform treatment of non-obviousness as the major substantive standard of patentability under the Convention on the Grant of European Patents. The analytical comparison Dr. Ullrich has made between the patent laws of Germany and the United States should provide a better understanding of the working of the national patent laws considered and the development of a proper standard of patentability under a unitary patent system operating with flexible criteria of patentability. His thesis that inventions to be patentable need only be unobvious and must not advance the art, is perplexing at first glance, but confirms the options taken by most modern patent laws. His criticism of preferential treatment of commercially successful inventions constitutes a serious warning against the dangers of the modern subtest approach to the non-obviousness judgment. Ullrich analyzes the reasons for the vicissitudes in the development of uniform standards of patentability under the national laws and appraises the function of non-obviousness from legal and economic viewpoints.