The articles has some examples on the difficult -> easy propagation. Like discovering what a company does well and creating a vision that uses it is difficult; joining all current projects and creating a slogan that fits them all to use as a vision is easy. Measuring impact is difficult; setting and measuring deadlines is easy.

There is more there. I leads to an "I know it when I see it" understanding. If I tried to compress it into a definition I would certainly miss lots of relevant details, at least without refining it for some time, so I won't.