3.3 p-t-k iconism
Comparing 3.1.1, 3.1.2 and 3.2, a notable iconic tendency can be found:
labials are associated with the sky and the idea ’above’ [’on top of’ the mouth]
- dentals are associated with a position inside something [inside the mouth]
- velars are associated with the earth [down in the throat]
The most ancient and very productive triplet of roots is √pru ’up’, √tru ’inwards’ (see http://sindanoorie.net/glp/historical002.html), √ka ’ground’.