Presently, we perceive what our five senses can absorb, and they only allow us to attain a part of the universe called "our world." However, Kabbalists explain that we have the ability to penetrate much deeper. We can delve through our world into nature and perceive the Upper World. Let's take a closer look at how we can do this.
We perceive our world through our five senses: sight, sound, smell, taste, and touch. We also build physical instruments such as microscopes or telescopes that widen the range of our senses' perception. But all the instruments we create can only expand our senses' perception and hence they can't let us perceive something beyond the reality called "our world."
Again, all investigations we conduct in our world are confined to our five senses. And as long as we are confined to them, we cannot begin to see, feel, and understand what lies beyond our senses.
Our imagination is also a product of our five senses and the experiences which stem from them. We cannot imagine an object or a creature unless it resembles something that our five senses are familiar with.
For example, if you ask someone to draw an alien from another planet, he will draw it according to the elements he is familiar with from our world. And if you ask someone to describe a fantastical scenario, he will no doubt describe something which is fundamentally very similar to this world.
We all live in a small world and are not able to feel or imagine anything beyond it. And since our science and philosophy are also limited to the perception of our five senses, they too cannot help us understand what lies beyond this world. Therefore, to get behind the scenes of our world and recognize the forces that affect it - we need a new sense.
The wisdom of Kabbalah offers a person the method to develop his latent, additional sense, called the "screen." Using the screen, one can penetrate through our world and reveal deeper, inner layers of reality, which influence our level of reality. Hence, the Kabbalists call these layers "Upper Worlds." These worlds are like the layers of an onion, where our world is in the midst of all the worlds.
To summarize, we naturally feel only the innermost sphere in all of existence, but Kabbalists explain that 'this world' is just a small fragment of the true reality. It's the fragment we are able to feel with our inborn five senses. But if we develop the additional sense called "the screen," we will feel the Upper Worlds that Kabbalists feel. This is what Kabbalah teaches: how to acquire the screen.