"We have different sub-regions of an early IE world, scattered in space from the Baltic to Anatolia and east across the European steppe. . . . To unify these disparate geographical elements together into a single 'unified theory' seems to be as distant to those seeking such a goal in Indo-European studies as it is for physicists."
January 1, 1970
https://en.wikiquote.org/wiki/Proto-Indo-European_homeland