Four Seals

There's an excellent book by Dzongsar Jamyang Khyentse called What Makes You Not A Buddhist. In it he elaborates on the four seals.

The Four Seals according to him are as follows:

1. All compound things are impermanent.
2. All emotions are pain.
3. All things have no inherent existence.
4. Nirvana is beyond all concepts.

These are all very deep and intense truths which he elaborates in his book, challenging many assumptions about American culture and the American dream. Reading it on retreat has been a deep and profound experience for me.