Think about it: humans interpret language. Language is there to be interpreted. By talking at and listening to each other we run eachother by remote control. Language is this remote control architecture by which we can anticipate and coordinate with eachother.
I open my mouth because I have faith that it's worth my effort. By making sounds, of greeting or conciliation, I can diffuse tension and create goodwill. That's because I can utter sounds that will create mental images in you, sometimes of great power, even though I did not put them there. That's the hall-of-mirrors of convention -- this set of that-which-I-know-that-you-know(-even-though-I-couldn't-say-why-it's-just-what's-there-...-y'know?) -- that makes it all tick. The memeplex is built upon convention; this hall of mirrors that comes straight out of protein and is structured just as tightly.