Hay is for Horses
Early in the book, we're confronted with two differing opinions of horses. Albert worships them; his drunk father thinks they're "obstinate and stupid" (1.14). Later, two minor characters get into a similar discussion about the values (or lack thereof) of horses. One says that horses "personify all that men try to be and never can be" (14.3); the other counters that they're simple creatures "controlled by a very little brain that can't think beyond food and drink" (14.3).
If you think about it, the same arguments can be made for many people, too—especially people at war. Whether soldier or civilian, war can change people, bringing out the best or worst in them. Some men are heroes, others are "wretched creatures" (14.3), and some are just trying to live to another day, motivated by what little food, drink, and shelter they can find.
Whichever side of this debate you find yourself on, one thing is certain: the horses in this book make us question our own human nature.