Outside physical world is perceived by mind through sense organs - eyes, ears, nose, tongue and skin.

What all we say outside physical world is nothing but the projection of mind in mental forms; perceptions.

Thus as far as human being is concerned the outside physical world is mere perceptive phenomenon. Its existence is in the form of mental impression.

Human being undergoes four phases or conscious states of mind knowingly or unknowingly. Outside physical world is a series of perceptions of mind in wakeful mental phase through sense organs appearing on mental screen.

What all a human being says outside physical world is, his mind's perception through sense organs in wakeful phase. Thus all physical world dubbed by human being existing is mere perceptive projection of mind as far as individual is concerned.

And he acts and reacts through action organs - movements of hand, leg, vocal chords, reproductive organ and bowels. Human beings communicate through action organs in Wakeful phase of mind.

Similarly what all perceived by mind through mind in Wakeful state is recorded as inner mental world. The tuning of mind to this inner mental world - the impressions of outside physical world - and retrieving them is nothing but a thought or feeling. This phase or conscious state of mind creates dream state of mind.

In this state of mind the mind is not tuned to sense organs. But action organs will be active according to thought or feeling or mental functioning or perceptions.

Also the cognition -related experiences are recorded and retrieved by mind in Wakeful and dream phases of mind.

The collection of records of these cognition-related experiences identifying individuals with their self-consciousness, constitutes the individual's memory.

The simultaneous working of wakeful and dream phases of mind together with active sense and action organs, constitute the cognition and communication processes of humans.

When mind is taking rest and no mental functions are taking place, sense and action organs are not tuned to the mind and are dormant, the phase of deep sleep of mind or Sushupti is created. No cognition, communication or thinking, feeling, activating memory, takes place during this phase. Mind is not in working phase or state or mode.

Then there is the fourth conscious state of mind rather mind-transcending phase, when, then mind is tuned to sense and action organs and is in a ready state to function but not in functioning state. If willed mind functions. But mind is not in a functioning state and is in rest phase.

This is called Wakeful-sleep or Jagrat Sushupti phase of mind.

Human mental functioning starts after awakening from deep sleep, first memory getting activated and egoistic mind instantly appearing, starts thoughts and feelings according to the experience activated. The appearances of inner mental world and outside physical world - through tuned mind to sense organs - simultaneously take place.

These two appearances are simultaneous and are mere perceptions or thought forms. Cognitions and communications start happening through sense and action organs, rather deep sleep is converted to dream and Wakeful conscious states of mind.

Because sense organs activated by tuned mind function, we see, hear, smell, taste and experience the touches and hotness or coolness. So all outside physical world is perception of mind through sense organs in Wakeful state of mind. It is a mere appearance on mental screen.

This appearance has been called as Mithya or unreal or illusion by Sankaraacharya.

Not the outside physical world.

(If in wakeful phase of mind either sense organs are defective - blind, deaf, etc. - that part of outside physical world is absent to the individual. Either scenes, sights to blind and sounds to the deaf doesn't exist to him and can't and don't be form of inner mental world; or mind is not tuned to outside physical world through sense organs - the individual is in dream phase of mind, the outside physical world doesn't exist for him.)

In dream phase of mind, the mind is tuned to inner mental world.

And thoughts and feelings are retrieval of impressions of perceptions of outside physical objects, created as inner mental world, caused earlier through sense organs.

The simultaneous existence, appearance and interplay of wakeful and dream conscious states of mind do all the mental functions and facilitate cognition, re-cognition and communication processes to happen.

This is the way mind works and our inner mental and outside physical worlds are. Both are appearances on the mental screen as thoughts, feelings and experiences in a forward and reverse way, in speaker and listener. These appearances are stated as unreal in Advaita thought.

This is the essence of the famous Advaita expression:

What is always present is Brahman
as Awareness and individual
is same as Brahman
and is not different.

Meaning:

The individual bereft of self-consciousness is Pure consciousness or Unoccupied Awareness or Content-free Contentment.

An individual as I is not a person but is Conscious awareness sans activated memory, feelings, thoughts, cognitions or communications. The real identity of I is experience of Peace, Bliss, Silence and unfilled Consciousness.