God dwells and is present substantially in every soul,
even in that of the greatest sinner in the world.
And this kind of union is ever wrought between God and all the creatures,
for in it He is preserving their being: if union of this kind were to fail them,
they would at once become annihilated and would cease to be.
And so, when we speak of union of the soul with God,
we speak not of this substantial union which is continually being wrought,
but of the union and transformation of the soul with God,
which is not being wrought continually,
but only when there is produced that likeness that comes from love;
we shall therefore term this the union of likeness,
even as that other union is called substantial or essential.
The former is natural, the latter supernatural.
And the latter comes to pass when the two wills -- namely that of the soul and that of
God -- are conformed together in one,
and there is naught in the one that repugnant to the other.
And thus, when the soul rids itself totally of that which is repugnant to the Divine will
and conforms not with it, it is transformed in God through love.
(Book 2, Chapter 5, Paragraph 3)
In thus allowing God to work in it,
the soul ... is at once illumined and transformed in God,
and God communicates to it His supernatural Being,
in such wise that it appears to be God Himself, and has all that God Himself has.
And this union comes to pass when God grants the soul this supernatural favour,
that all the things of God and the soul are one in participant transformation;
and the soul seems to be God rather than a soul, and is indeed God by participation;
although it is true that its natural being, though thus transformed,
is as distinct from the Being of God as it was before...
(Book 2, Chapter 5, Paragraph 7)