Beg to differ, but in context, the meaning is that the borders of Texas weren't fixed by treaty but by revolution. The sentence before the paragraphs you cite reads, "The extent of our teritory in that region depended, not on any treaty-fixed boundary (for no treaty had attempted it) but on revolution." What the next two paragraphs basically say is "And that's fine."
He then goes on to say, "After this, all Mexico, including Texas, revolutionized against Spain; and still later, Texas revolutionized against Mexico. In my view, just so far as she carried her revolution, by obtaining the actual, willing or unwilling, submission of the people, so far, the country was hers, and no farther."
So, he cites two revolutions involving the same territory , both of them bloody affairs, not abstract concepts. As I said before, the legal and philosophical background to the concept of the Right of Revolution is based in Locke and Blackstone, who both wrote out of the experience of the English Civil War, the "Great Rebellion." An interesting point you could possibly make would be that it was the north that had a bloodless revolution in the election of 1860, then "carried her revolution, by obtaining the actual, willing or unwilling, submission of the people, so far, the country was hers" over the south.
Strange that you would consider that legitimate, but Southern secession illegal."
Again you're mixing concepts. I'd find a slave rebellion in the south to be perfectly legitimate in a moral sense. I'm quite certain, though, that it would have been illegal.
I can't beleive that Lincoln considers war to a a sacred right, nor can I believe that he's an advocate for massive revolts/wars across the globe. Anyone desiring world war would be insane.