The Tirukkural (or Kural, for short) by Thiruvalluvar is one of the acknowledged highlights of the Tamil literary tradition, which spans 25 centuries. The new English translation by Thomas Hitoshi Pruiksma has been highly praised, and I recommend it.
I usually find “wisdom literature” (didactic, aphoristic poetry) hard going, regardless of its background or main teachings. But The Kural is widely reported to be subtle, paradoxical, allusive, and lovely in Tamil, and Pruiksma’s English has those virtues. For instance, here is a paradoxical verse about renunciation:
Hold to the hold of one who holds nothing—to hold nothing Hold to that hold 
And here is an example of a memorable metaphor:
Riches attained by those without kindness—like milk Soured by its jug 
I don’t know another unified poem that encompasses ethical directives (part 1), advice for monarchs (part 2), and erotic verse (part 3). The whole poem concludes with a section on “Sulking and Bliss,” which recommends playing hard-to-get. The narrator is never identified, but part 3 seems to weave together the voices of two lovers, their friends, and other characters, almost like a drama:
Though he’s done no wrong pulling back Brings him closer  ... Even free of wrong there is something in keeping From my love’s soft arms  Sweeter than eating—having eaten—sweeter than loving— Sulking in love  ... Sulk my bright jewel—and may our night Of pleading be long 
The text was probably complete by 600 CE. There’s a long tradition of identifying Thiruvalluvar as a Jain, although many other religious traditions (including, implausibly, Christianity) have claimed him. David Shulman reminds us that we know nothing about the author, even whether a single person wrote The Kural. (Almost certainly, the text incorporates numerous quotations.) Shulman writes, however, that the milieu is the “mobile world of the [South Indian] city, with its face turned toward international seaborne trade and also toward heterodox religions, like Buddhism and Jainism, carried throughout South Asia and beyond by wandering monks and holy men.” Furthermore, the text largely avoids the kinds of claims that typically divide religious traditions, such as the identities and roles of deities or the origins and end of the world. A Buddhist, a Shaivite, or a Stoic could embrace The Kural, and that may be intentional. After all:
Delivering the complex simply and discerning What others say—that is knowledge  ... Those who can’t speak a few faultless words Love to speak many words 
In the sections on personal ethics and the good life for regular people, The Kural advocates what Owen Flanagan has called (writing about Buddhism) “equanimity-in-community.” We should cultivate inner peace by restraining desire and craving. But we should use everyday ethical interactions to fill the space that might otherwise be occupied by those vices. The Kural emphasizes hospitality, generosity, friendship, forgiveness, nonviolence (ahimsa), “husbandry” (in the sense of cultivating one’s land and animals), and family. I didn’t pick up anything about yoga, meditation, or ceremony and ritual. Instead, passages like this evoke sociable, generous members of communities who are not overly concerned about their individual desires:
A well of abundant water—the wealth of the wise Who love the world A tree bearing fruit at the heart of town—wealth In the hands of good people [215-6]
The implied reader is generally male, and the division of roles is patriarchal, but we can modify the advice to be more egalitarian. The text charts a middle way between pleasure and renunciation. An adherent to a Hellenistic philosophical school, such as Stoicism or Skepticism, could endorse much of The Kural, except that nonviolence is more explicit and prominent here than in late Greek philosophy.
The long middle portion of the book–on leaders, politics, and governments–belongs to the “mirror of kings” tradition: encouraging rulers to be responsible and moderate. Although The Kural strongly urges nonviolence and vegetarianism as components of personal ethics, it depicts good leaders as honorable and effective warriors. Some of the advice here is about how to win wars and retain power.
The third part comes as a surprise, because it is suddenly about ardent sexual desire, which had been criticized earlier. The style is more lyrical now, and the speaker is sometimes female.
Apparently, in classical Tamil love poetry, the lovers wake up under separate roofs, spend the day together (perhaps illicitly), and part unwillingly at twilight, which is a confusing time of shadows and dimness. In this verse, the “it” is passionate desire:
At dawn it buds—all day it swells—and at dusk It blossoms—this disease 
And here the (presumably female) lover resents the evening but tries to summon some empathy for it:
Is your husband hard-hearted like mine—bless you
You wretched bewildering evening 
Although love is a “disease” that causes much sighing and suffering, surely the conclusion of The Kural celebrates it.