[bookaway]

> He also doesn't even list a specific example of something he wants to say but "can't."

That's because he's making the general point that in every era there is always something "that can't be said" that then later becomes accepted in another era, and therefore people should strive to find truths that are as "era independent" as possible. He specifically mentions Galileo, pre-Civil War South, and Germany in the 1930s. I'm sure you can imagine a few things "that couldn't be said" in those environments or eras. The essay was written in 2004, when it wasn't unheard of of people were getting fired for their various takes on 9-11 and the wars on terror either, so I doubt it was hard for a reader to "imagine" some examples to understand the point.