The last two chapters of Anthem are, arguably, the most important of the book. Equality 7-2521 opens Chapter 11 with a veritable trumpet blast of first person pronouns making us aware that he's finally discovered the "Unspeakable Word." Though the plot is essentially over, the last two chapters, and in a way the whole book, have been building up to this point. And then begins Equality 7-2521's "song of praise" to the human ego, as he starts to tell us in ecstatic language the new understanding he's arrived at. In the process, he even gives us a basic crash course in Randian egoism. (For some of our explanation of the particulars, see "Philosophical Viewpoints" in the "Themes" section.)
The take-away message of the ending is that the individual human ego is the highest and most holy thing that exists. In Equality 7-2521's view, the ego is what gives meaning to the world, and what gives human beings a reason for living (their own happiness). The "anthem" Equality 7-2521 recites to the ego is meant to make us readers feel just as awe-inspired and worshipful towards the ego as Equality 7-2521.
The last chapter in particular is also meant to issue a warning to us about the danger of losing sight of the sanctity of the individual ego: individuals must not sacrifice their freedom and happiness to collectivism and the "great WE." Rand herself saw this as a growing threat when she wrote Anthem (see "In a Nutshell"), and it's hard not to detect the note of criticism in such phrases as: "But I still wonder how it was possible, in those graceless years of transition, long ago, that men did not see whither they were going, and went on, in blindness and cowardice, to their fate" (12.20).
The ultimate message of Anthem's closing pages is one of hope and confidence. Not even the horrific society in which Equality 7-2521 lived was able to extinguish the human ego completely. Now, it looks like Equality 7-2521 himself is preparing to strike back and free all of those who suffer under the yoke of collectivism.