"I" is The Obstacle

What is the obstacle to discovering Ultimate Truth?

There is a beautiful Sūfi poem in Hindī:

Ek Bastu, Ek Biṁb Hai
Main Dono Ke Bīc (Beech)
Jab Main, Main Se chūṭ Gayā
Sāhib Rahyo Samīj


Everything is one. All matter is the same. When we look behind all matter, still, existence is one.
Because I am here surrounded by all matter, when “I” look at it, everything looks different,
But when I come out of the grip of the “I” (ego)
Only God, pure existence, remains there in front of me.

What exactly is this poet talking about?

We can’t see the forest for the trees!
There is only one truth. Everything else in the world is just “matter”. Matter; that, quite frankly, doesn’t matter. Essentially, all matter is the same. Things may look, smell, taste, sound, or feel different from one another, but that is just because our senses are limited. When everything is distilled down to its pure essence, everything is exactly the same. To put it simply, everything is energy.
Because we are surrounded by matter and we depend on our senses and mind to experience our surroundings, everything we see around us seems to be unique. Even when we try to look more closely, dissect what we see, and examine the components of our surroundings, everything looks different. Through our senses we cannot identify the oneness that surrounds us. It is only when we allow ourselves to separate ourselves from our mind and our senses and experience the world through our TRUE self, the Ātman, self, that we can see that everything is part of the same oneness. And it is at that time that we can see and understand that this Oneness, this same existence, is God; Ānand ; Bliss; Truth.
The mind doesn’t even have the ability to register Oneness, because the mind can only see things in parts. The mind is just like a computer screen. It actually creates thoughts and images in a similar way to putting together millions of pixels. So because of this, the mind is always dissecting everything that it gets from the senses into pieces, labeling those pieces, and filing them in our database for future reference. This is the job of the mind, and it serves a very useful purpose in our day-to-day existence!
What we all need to remember is that fact that you are NOT your mind. Every person is a unique soul, a pure soul that is temporarily occupying a particular body and mind. When you can learn to separate your true Ātman self from your body and mind, you can begin to experience this Oneness.
This is what is meant by removing the “I”. This is in reference to the “I” that we imagine ourselves to be; our ego. When we remove the ego, remove the mind, and remove the body, then all that remains is the observer, the experiencer, the pure soul: the Ātman self.
Therefore, everything that you think of as “yours” is not yours. If you are holding “your pen,” you are not “a pen”; you are yourself, and you possess a pen which is a separate entity. The same is true when you talk about your mind and body! So when you remove everything that can be declared as “yours” (which as we’ve seen is not synonymous with “you”), then you are left with the Ātman self. This is your true ‘I’. It’s simple deductive reasoning!
So what the author is saying in his poem is that everything is one, but being entrenched in the worldly matter that surrounds him, he interprets everything as being different. But when he removes the ego and mind from his true existence, all that remains is the Oneness that is God or Ultimate Truth.