People communicate effortlessly, but this simplicity is an illusion. (NB: The irony of this position in Minsky's book is the story -- confirmed by him in a Scientific American profile published in recent years -- that he viewed vision as being so simple that he assigned it as a summer computer programming project to an undergraduate student.)
Communication really seems to involve constructing structures in the minds of listeners. How? First, build a new version of the structure in your own mind. Second, with each step in 1), say the corresponding verbal expression so that the listener can copy the steps!
"To be able to do that, Mary must have learned at least one expressive technique that corresponds to each frequently used mental operation. And Jack must have learned to recognize those expressive techniques -- we'll call them grammar-tactics -- and to use them to activate some corresponding isonomes and polynemes.
NB: This turns the table on critics of protocol analysis! Minsky is saying that communication depends on our ability to create or interpret thinking aloud protocols.