"And God said, 'Let there be light, and there was light,'" "The light at the end of the tunnel," "You are the light of my life," "I saw the light." If you recorded the times you heard "light" referred to each day, you would most certainly find hundreds of references to it in one form or another. Phrases like: "in light of," "shed some light on," "illuminated" and "radiance" are metaphors often used to describe thoughts about wisdom, hope and goodness. We say "an enlightened person" to describe someone who is wise and who is able to see the world in a virtuous or Godly way.

We are cheered by the light of the sun and we plan vacations in places where we can relax and enjoy its radiance. We are attracted to the warmth of firelight and we gather around the light of campfires. As human beings, we relate to light in an emotional, almost sensual way.

It’s hard to imagine that after thousands of years of research, scientists are still not exactly certain about the nature of light. There is, however, no argument that light is vital as the wellspring of life on earth.

It is no coincidence that just the thought of light produces such profound sensations. The wisdom of Kabbalah teaches us that there is, in fact, a "spiritual Light" which affects us even though we are not aware of its presence. This Light is a spiritual essence. It is a property of the One who created us – the Creator.

The great 16th century Kabbalist, the ARI, wrote in his book The Tree of Life:

"Behold that before the emanations were emanated and the creatures were created,

The Upper Simple Light had filled the whole existence.

And there was no vacancy, such as an empty atmosphere, a hollow or a pit,

But all was filled with Simple Boundless Light."

What is the nature of the spiritual Light? Just like physical light fulfills us in physical ways, making us feel warm and comfortable, so the spiritual Light fulfills our spiritual needs, the needs of our souls. Kabbalists explain that while living in our world, a person can fill his soul with the spiritual Light and thereby experience boundless joy and fulfillment.

When one's soul becomes filled with Light, one senses an internal realm called "the Upper World." That is, one feels a sensation that is completely beyond what we feel in the physical world. The difference can be conveyed in the following way: In this world, all of our perceptions evolve naturally, through our five senses. But if you look carefully at the world around you, it becomes obvious that we encounter and are affected by many forces of nature that are invisible to us. For example, the oxygen we breathe is invisible, but without it we could not survive in the physical world.

In the same way, "the Upper World" is a realm of reality that is imperceptible to our natural five senses, but we begin to feel it as our souls become fulfilled by the spiritual Light. Dr. Jeffrey Satinover, one of the scientists who made the movie "What the Bleep Do We Know!?" explains this from the point of view of quantum physics:

"Quantum theory shows that there is something working beyond mere mechanism, outside the physical world."

This is why Kabbalah is called "the wisdom of the hidden"—because it discloses the part of reality that is hidden to our five senses. It is a method enabling a person to fill his soul with Light, and simultaneously feel both the Upper World and our world.