The irony of human character
We like to think we're all hero and no villain, but the novel points directly at the fact that humans are complex and difficult to understand, even to themselves. For example, Commander Yu is simultaneously "good" and "evil," which is to suggest perhaps that balance is more important than purity.
The irony of the unnamed speaker
The entire novel is about the generational heritage or inheritance that the speaker received from his ancestry. It's intimate and expository from the speaker's point of view, so it's odd that the main character doesn't get a name. Perhaps this is an ironic indication that the story has its roots in the real history of the author.
The irony of cannibalism
We'd like to say, "Cannibalism is pure evil," but the author shows in a flashback that even dogs will resort to cannibalism when food is in short supply. The humans witness this as a testament to the true horror of nature, and the true horror of animal life. Cannibalism isn't demonic or something, it's biological, "built-in." That adds a difficult layer onto the question of human "goodness."
The irony of war
War itself is on the table for discussion in the novel. Just like death, war is perplexing to the young narrator who doesn't quite understand how his own ancestors could have participated in warfare.
The ironic duality of time
Time is the thing that takes sorghum and makes it into wine. Time is like God in that respect, because both yield good things sometimes, and bad things other times. When the sorghum is defeated by a new variety of sorghum in the ending of the novel, that is also time. Time itself is dual, like man.
