Buddha’s teaching is that samsara’s hallmarks, the “three laksanas”, are impermanence, the lack of self-nature (emptiness) of things, and dukkha.
We usually think that the truth of impermanence means that things are impermanent. If we reflect a little deeper we realise that the two ideas are incompatible: the more impermanence is true, the less we can have confidence in things. The concepts are contradictory: if there is no permanence, no things are possible.
At the level of awareness, which is never still, there is such complete impermanence that we must concede the emptiness of the notion of things. Impermanence is true, things are not. The word “impermanence” ceases to apply since there is nothing that could be said to be impermanent.
If impermanence is true, things are not. If things are not, we are not (as a persisting self). Ooh, conflict with our story! Suffering is the conflict of story with truth. Our Heart-barometer is Sensitivity.
So the three laksanas are really one: they are how experience is (and the effect of not seeing how it is, a-vidya). Impermanence means no things, emptiness means no things, experience is happy like this! But constructing a conflicting story creates dukkha. That story is the invention of a self, a ‘thing’, with permanence. It relates to other ‘things’, which must have some permanence, even if not eternal. So we create duration, time, against which our things are impermanent. Including our body.
Not-seeing, avidya, leads directly to suffering, dukkha. This is the message of the (more detailed) twelve links of dependent origination, pratitya-samutpada, but the three laksanas point this out very simply. The solution is to discover our direct un-storied experience, our Awareness, which actually feels more true than our self-story, and trust that. It’s a simple but long road to finding out where we always were!
N.B. As always, do not take statements of the non-existence of an idea of ‘self’ as a theory to adopt, because the actual situation must be known as experience: it is inconceivable because it is beyond concepts. It is not experienced as nihilism, as not being anything, it is something infinitely more significant, it is the revelation of Buddha Nature.
Similarly “form is emptiness, emptiness also is form”, and appearances do appear, with a dependent relationship to each other (paratantra).
Relative truth is the consistency (“truth”) of the relativity between apparent things.
Pieces of Five 