Why did the Light create us opposite to it, like a shadow on its background? This is because it is impossible to attain the Light itself; we can only attain it from its oppositeness, as it is written, “The advantage of the Light is revealed from within darkness.”
As creation, we do not feel the phenomenon itself, but are able to perceive something against its opposite, such as sour and sweet, cold and hot, etc. It’s precisely the polarity of experiences that creates a sensation in us.
This is why the Light had to create us in the form of darkness, opposite to it, and then help us to get to know it from this darkness. This way, it becomes clear how the Light acts upon us.
Its action is expressed in two ways. On one side, it increases my desire, and on the other, it creates a sensation of the One who affects it. In the first case, the Light acts through pleasure, and in the second, it is like it introduces itself.
This is the way my desire develops. It grows to a certain degree and begins to recognize Who develops it. Then, it grows even more, and I already begin thinking about what will happen with me further, how I can become similar to Him and acquire His properties.
In other words, my desire not only becomes bigger, but it also grows in quality. In the end, it turns into a very big desire. Its magnitude becomes equal to the pleasure that acts on it, while the quality which I desire is what the Light wants.
From Kabbalah for Beginners, “Light” 12/8/10