"Speaking" looks at how language affects how we refer to blue. Gladstone once had a theory that ancient Greeks couldn't perceive blue to explain why the word for blue is not used. But further studies would show that it is an effect of how language develops words for colours instead. Other studies works show that in a small way, having words to refer to different shades of blue can have an effect on whether people can more easily see shakes and shades of blue in experiments.