What does “protecting each other, right in the center a few pages glow a long time” mean?

The poem "Burning a Book," by William Stafford, is interesting in that its moral is not what we might perhaps expect, and its outlook is somewhat bleak--"truth, brittle and faint, burns easily." However, the opening lines, with their statement that "right in the center, a few pages glow a long time," suggests that the very core of any truth will be the last to disappear, no matter what is done to it. While a story can be manipulated and censored, its core tenets will "protect each other," glowing in the embers for a long time before they are finally forgotten. Even when the fire has completely burned out, some element of most stories will remain--"you can usually find a few charred words in the ashes."
Ultimately, what Stafford's poem indicates is that the truths that are really worth knowing do not need to be written down: likewise, many lies, both written and unwritten, flourish. Meanwhile, there are libraries' worth of truths that have not only never been committed to paper, but have gone "unthought."