The history of Model Theory can be traced back to the work of Charles Sanders Peirce and Ernst Schröder, when semantics started playing a role in Logic. But the first outcome dates from 1915. It appears in the paper Über Möglichkeiten im Relativkalkül (Math. Ann. 76, 445-470) by Leopold Löwenheim. The period from 1915 to 1935 is, in words of R.L. Vaught, extraordinary. The method of elimination...