Horace - Book III

All of the poems in Book III of Horace's Odes are in Alcaic meter, which is named after Alcaeus. It is fitting that he chooses this meter (in the only book so far to have a consistent rhythm) as his first six odes focus mainly on politics. His social commentaries of Romans draw on their use of wealth, their raising of young boys, military matters, Augustus's power, and moral corruption, among other things.
Politics is not necessarily the over-arching theme throughout the book, however. More prevalent are those of moderation and virtue, and, on a similar note, poverty and rural life. Horace attempts to convince the reader of the value of a simple life, and more importantly, that he himself lives it. Horace's idea of moderation is shown as early as poem 1;
"...But soothing sleep does not despise
the humble homes of country people...
The man who wants enough and no more
is not disturbed by stormy seas...
Why should I give up my Sabine valley
for riches which bring more labor?"
In these fragments of Ode 1, we see that Horace thinks of a life in moderation as a life of peace, which is not "disturbed" or laborious. He also views country people as exemplifying the values of the Roman people (such as humility) and imagines their lives as this peaceful, poor one. (Clearly he has never actually been around poor people in the country, nor has he lived that life, or he would not say it was peaceful.) Similarly in poem 16:
"The more a man denies himself, the more
he will receive from the gods. Naked, I go to join
the camp of those who desire nothing, and long
to desert the ranks of the rich."
Here Horace claims that those who allow themselves to be poor, and are happy in that poverty, will be given many good things by the gods. Again, this does not seem to be the case for the majority of the lower class in the Roman Empire, but it works for Horace. Likewise, poem 24 discusses how greed can grow, and that once a person looses his virtues, he always wants more riches and more wealth no matter what he has already.
The intent of these poems seems to be largely to provide a lesson for the Roman people and teach them to be good citizens. Also on that note, he focuses highly on virtue, as in poem 2 where he instructs a youth to seek the army and desire to "die for one's native land" (a line which so many poems have been based on). He says that:
"Virtue opens a way to heaven for those who deserve
not to die. She dares to take the forbidden path,
spurning the vulgar throng and the dank earth
with soaring wing."
Again, this idea of reward for good behavior - by  being just, being virtuous, living in moderation, you will be the perfect citizen and be loved by the gods. Punishment can also be a good motivator, however, as he warns in poem 24 that
"Infidelity
is a sin against the gods. Its price is death."
Horace also says that someone who is truly virtuous will "rein back our wild licence" and reminds us again that the Roman people are full of vices - they must focus on moderation and virtue.