In Reality Creation does not exist (TANYA)-nullified as to its source

Why do we perceive tangible existing beings as separately existing when they are nullified in their source? The example of the Sun and its rays is extremely apropos to illustrate that all we perceive is as a chimera and that G-d's force must continuously be within them and that, in reality they cannot exist without this force constantly re-creating them.This illustrates G-d's capacity for tzimtzum, or contraction of the divine force to create and sustain the finite creation.

Why do we not actually see existence nullified in their source? Th 4th chapter of Tanya explains this creative phenomenon of Havayah Elokim as Tzimtzum.

Since the Divine activating force responsible for the existence of created
things must continuously be present within them, they are completely nullified
in their source. This means, as the Alter Rebbe explained in the previous
chapter, that in reality they do not “exist”.
Why, then,
do we nevertheless perceive created beings as enjoying a tangible “existence”? —
Only because we are unable to see or comprehend the Divine utterance that is
contained within each created thing and that calls it into being.
The
Alter Rebbe illustrated this by considering the sun’s rays. When they are not
within their source, the sun, but diffused throughout the expanse of the
universe, they are perceived as having independent existence. However, when they
are contained within the sun-globe they clearly have no such “existence” at
all.
The following question therefore arose: Since created


beings, unlike the sun’s rays, must constantly have
their source within them, why do we not actually see how they are completely
nullified in their source?
In order to answer this question the Alter Rebbe
wrote that a certain preface would be necessary — and hence this, the fourth
chapter, now elaborates on G‑d’s capacity for tzimtzum, or contraction.
כי
הנה כתיב: כי שמש ומגן ה׳ אלקים
It is written,1
“For a sun and a shield is Havayah Elokim.”