Isotype has been a purely historical phenomenon for about ten years. It proposed a system for presenting information in visual form; but how can designers now learn from this work ? It is argued that Isotype cannot be fully articulated as method, and that it should be understood rather as approach. Such an understanding must come from 'authentic ' historical presentation, which avoids imposing current concepts. Some inappropriate treatments are cited. But, as the revival of the 'transformer7 suggests, Isotype can still be a fruitful influence. To help further study, the documentation of the subject is surveyed.