Hi Akvan, Johnny,
Actually, anicca nature is INHERENT in the things in our world. It is rooted in the udaya (arising), vaya (destruction) of a sankata, and also the viparinama nature of a sankata in between udaya and vaya.
This is why Udayavaya Nana is of importance for the Sotapanna stage; see, “Udayavaya Nana“. Those can be called characteristics of nature or marks of existence or Tilakkhana.
Understanding those characteristics of all sankata are helpful in cultivating the anicca sanna. Reading about the anicca nature may help remove the ditthi vipallasa about anicca. But cultivating the anicca sanna needs a bit more work. This is what I will be discussing in the next desana.
Pancakkhandha are mainly mental; see “The Five Aggregates (Pañcakkhandha)“.
But those mental impressions arise from our interaction with those material things (sankata) out there in the world. Those material things (or each person’s pancakkhandha) do not have dukha in them. It is only when we make cravings (or upadana) those things (panca upadanakkhandha) that we become subjected to dukha (suffering). It is helpful to comprehend the udaya, vaya, and viparinama nature of sankata, in order to see the root causes of anicca nature.
Pancakkhandha is like a bottle of poison sitting on a table. One gets into trouble only if one takes it and drinks from it (panca upadanakkhandha). An Arahant has pancakkhandha, but no panca upadanakkhandha.
This is a deeper aspect of anicca that I will discussing in a future desana.
Now, I do not want to scare people by saying that all these are requirements for the Sotapanna stage. These are just different ways of looking at the anicca nature. One may “see” anicca nature in many different ways, and understanding more ways is better to remove the sanna vipallasa of a nicca nature. it is also true that one can become a Sotapanna without even having read about Udayavaya Nana. But it depends on whether one has done those investigations in past lives. It is similar to the case where jhanas come easily to those who had cultivated them in previous lives.