Emergence of the Four Frames of Reference:

The Buddha once explained the profundity of causality like
this:
Arising of Nutriment induces
the emergence
of the Body...
Ceasing of Nutriment induces the passing away of the Body...
Arising of
Contact induces
the emergence of
Feeling...
Ceasing of
Contact induces
the passing away of Feeling...
Arising of
Naming-&-forming induces
the emergence of Mind...
Ceasing of
Naming-&-forming induces
the passing away of Mind...
Arising of Attention induces
the emergence
of Phenomena...
Ceasing of Attention induces the passing away of Phenomena...
Therefore is considering,
contemplating, analyzing, and recollecting:
1: Body merely as a transient form grown up on
food;
2: Feeling only as passing emotion arisen from
sense-contact;
3: Mind just as changing mood
emerged from
naming-&-forming;
4: Phenomena only as momentary mental states
created by attention.
It is a crucial necessity to reflect on these 4 facts
repeatedly, and thoroughly.
This is called initiating and developing the
Four_Foundations_of_Awareness,
which, in itself, is the mental treasure par excellence, that
leads steadily,
and directly to the
Deathless Element:
Nibbāna...

More on these
Four Foundations of Awareness (Satipatthāna):
What is Right Awareness?,
Four_Foundations_of_Awareness,
Awareness_Sati,
Satipatthana,
The_Awareness_Ability.

Source: The Grouped Sayings by the
Buddha. Samyutta Nikāya V 184
http://store.pariyatti.org/Connected-Discourses-of-the-Buddha_p_1379.html
https://What-Buddha-Said.net/library/ati_website/html/tipitaka/sn/index.html