I had the most trouble comprehending the large section in chapter 5 of Babel pertaining to co-articulation. The basic definition was simple enough--some letters influence the pronunciation of the letters around them. But I had to reread just about every sentence in the entire section about 4 times, underline, and sometimes draw small diagrams to really understand the specific examples. Perhaps this phenomenon is so un-salient to me as a speaker, that I had trouble wrapping my mind around it. And once I finally did limp away from that section of reading, I was greeted with "well, maybe co-articulation happens sometimes...and maybe it doesn't really matter." Is it really possible to get at the fundamentals of language by hacking it to tiny bits (i.e. the sum will always be greater than its (possibly meaningless) parts)? What can we even concretely say about syllables?