 Categorisation of colour impressions under a small number of generally applicable ("abstract") terms like "blau" and "rot" was, for him, the outcome of long evolutionary development, and only a minority of languages had achieved this.Specifically, he found it remarkable that the German language had mastered ("bewältigt") the entire world of colour with only eight abstract colour words.Weisgerber claimed in 1929 to have discovered a significant restructuring in the field of visual impressions.