What does Drummond (1980) discuss about language continum

In his work, Drummond (1980) discusses the concept of a language continuum, which refers to the idea that languages exist on a spectrum rather than in distinct categories. This means that languages can blend into one another, with no clear boundaries between them. Drummond argues that this fluidity of language boundaries can have important implications for how we think about and study language diversity, as well as how we understand language change and evolution. He suggests that rather than thinking of languages as discrete entities, we should consider them as part of a continuum that is constantly evolving and changing.