Hi Raj,
In additional to what Lal shared.
“in what context the Buddha deal on the subject of anitiya or the constant changing aspect of ourselves and our surroundings.”
“Because anitiya or the constant changing aspects of ourselves and our surrounding is also an irrefutable factor of everything.”
Whatever you or anyone take anitiya, anicca, impermanence, etc . . . as . . .
From what I can understand what your asking . . . some things that you can look into are:
#1. Sankata
#2. Paticca Samuppada.