Hi All,
I believe in a theravadin context ground of being is referring to the Dhammapada verses 1 & 2.
dhammapada for contemplation wrote:1
All states of being are determined by mind.
It is mind that leads the way.
Just as the wheel of the oxcart follows
the hoof print of the animal that draws it,
so suffering will surely follow
when we speak or act impulsively
from an impure state of mind.
2
All states of being are determined by mind.
It is mind that leads the way.
As surely as our shadow never leaves us,
so well-being will follow
when we speak or act
with a pure state of mind.
but these verses do not mean that
ground of being is anything other than where we live, experience the world through,
maha-satipatthana sutta wrote:Contemplation of the Mind
And how, monks, does a monk dwell contemplating (the nature of) the mind in the mind?
Here, monks, a monk when a mind has passion knows the mind has passion,
or when a mind is without passion he knows the mind is without passion;
or when a mind has hate he knows the mind has hate,
or when a mind is without hate he knows the mind is without hate;
or when a mind has delusion he knows the mind has delusion,
or when a mind is without delusion he knows the mind is without delusion;
or when a mind is collected he knows the mind is collected,
or when a mind is scattered he knows the mind is scattered,
or when a mind has become very great he knows the mind has become very great,
or when a mind has not become very great he knows the mind has not become very great;
or when a mind is surpassable he knows the mind is surpassable,
or when a mind is unsurpassable he knows the mind is unsurpassable;
or when a mind is concentrated he knows the mind is concentrated,
or when a mind is not concentrated he knows the mind is not concentrated;
or when a mind is liberated he knows the mind is liberated,
or when a mind is not liberated he knows the mind is not liberated.
* * *
Thus he dwells contemplating (the nature of) the mind in the mind in regard to himself,
or he dwells contemplating (the nature of) the mind in the mind in regard to others,
or he dwells contemplating (the nature of) the mind in the mind in regard to himself and in regard to others,
or he dwells contemplating the nature of origination in the mind,
or he dwells contemplating the nature of dissolution in the mind,
or he dwells contemplating the nature of origination and dissolution in the mind,
or else mindfulness that ßthere is a mind is established in him
just as far as (is necessary for) a full measure of knowledge and a full measure of mindfulness,
In this way, monks, a monk dwells contemplating the (the nature of) the mind in the mind.
not Nibbana, or buddha nature which is also associated with this term, so although the term could be understood in a theravadan context it is not going to mean the same thing as it does in zen, or in its christian usage as meaning god or a metaphysical absolute (which the Buddha rejects.)