Even if we forget this when we are immersed into one moment of pleasure, each of us is aware that existence is filled with sufferings, worries, dissatisfactions of all kinds, and that these never stop. This characteristic (dukkha) which is obvious, is described in all schools of thought, in all religious systems.
The notion of impermanence (anicca) is less obvious. Nevertheless, it is also often described in religious and philosophical systems.
As to the characteristic of absence of a self (anatta), this is a completely new concept about which only Buddha talks. It is by far the subtlest and most essential point of all knowledge. It is the foundation of any understanding of the dhamma.
Refer to the three lessons on each of these three characteristics...
Author: Monk Dhamma Sāmi
Translator: Thierry Lambrou
Update: 2005, June the 14th