Random Thoughts

I sat down with a new music student this morning, he's 18 and has been playing guitar for over 4 years. Apparently he's pretty proficient at the guitar, however he doesn't know how to read any music. He knows nothing about note names, note values - nothing. How can that be? Is that like being able to speak a language but not being able to read or write it? It is a interesting phenomenon to me. I guess I learned to sing as a child before I could read music - is it the same thing?