Otto Neurath was the first, but together with Neurath, Arntz is considered to be one of the founders of Isotype. A simple word for ISOTYPE is pictogram and he made over 4000 of them. Gerd Arnyz is even in our days considered to be one of the great inventors of the pictogram. The strength is that one can immediately see the meaning of the picture/pictogram and in relation to numbers and other pictograms.
Picture from http://www.gerdarntz.org
Because he opposed to the Nazi party in Germany and made some political drawings and statements against them, he fled to Den Haag in 1934, where he joined Neurath and Reidemeister. The three of them became extremely productive and it is in the Netherlands that most of his books, pictorial statistics and pictograms were published. Living and working in Den Haag, Arntz was familiar with its museum and for this reason the Haags Gemeentemuseum could acquire a large collection of his works and still on the book markets, when looking thoroughly, you can even find some nice publications, but this is getting harder and harder each year. www.ftn-books.com has some nice publications and the book ZEVEN HOOFDZONDEN in which an original woodcut by Arntz is published together with 6 other originals.
It was about 10 years ago that STROOM had a nice exhibition on Arntz and Neurath and they made a spectacular poster for the exhibition which is also available at www.ftn-books.com