Think of the Saṃyutta Nikāya as a themed playlist of the Buddha’s discourses, neatly bundled by subject so it’s easy to dial in to whatever aspect of the Dhamma is needed. At its highest level, it breaks down like this:

• Seven “books” (vaggas), each gathering samyuttas—linked groups of suttas sharing a central topic.
1. Sagātha-vagga (Verses): short, catchy teachings often prefaced by poetic refrains.
2. Nidāna-vagga (Causation): dives into dependent origination, the “if this, then that” of becoming.
3. Khandha-vagga (Aggregates): analyzes the five heaps—form, feeling, perception, formations, consciousness.
4. Saḷāyatana-vagga (Sense‐bases): explores seeing, hearing, smelling… right through to mental phenomena.
5. Mahā-vagga (Great themes): big-picture topics like Brahmavihāra and jhāna practice.
6. Paṭicca-samuppāda-vagga (Dependent Origination): fourteen‐step chain showing how suffering arises and ceases.
7. Dhātu-vagga (Elements): the eighteen elements linking body, mind, and experience.

• Within each vagga are dozens of samyuttas—doctrines on point, each stacked with suttas that often repeat a core formula, like a TED Talk riffing on the same idea.

This three-tier structure (book → samyutta → sutta) reflects an ancient oral culture’s love of patterns and repetition. It’s surprisingly modern: much like browsing a podcast series by topic, these collections help practitioners zero in on impermanence, non-self or mindfulness of breathing, whether tackling burnout at work or seeking calm in a chaotic world.