The will to receive is the whole substance of Creation from beginning to end.
Baal HaSulam, “Preface to the Wisdom of Kabbalah,” Item 1
When we want to be impressed by something, whether emotionally, intellectually, or otherwise, we must be on the same “wavelength” with it and thus possess the same quality. For example, to detect radio waves, the receiver must produce the same wavelength, and only then can we detect the wave on the outside.
Nature’s overall force is a “desire to give,” to bestow, to impart abundance. Conversely, our nature is one of “desire to receive delight and pleasure,” a desire to enjoy for ourselves alone. Our nature is self-centered; it is how we were made, as Kabbalah tells us. In other words, we are in contrast with the upper force, opposite from it, and hence we cannot sense it.
Is there anything we can do to sense it? We cannot destroy our nature and our will to receive, nor do we need to. We should continue with our lives as usual, and at the same time acquire new tools of perception.
But where can we find such an instrument that will supplement us with the new nature—to give—in addition to our original nature—to receive? Here, the wisdom of Kabbalah comes to our aid. At the moment, we are receivers. We absorb. And if we do give something to someone, it is only after we have calculated that it is worthwhile for us to do so. Our nature prevents us from giving without receiving something in return. It simply denies us the energy to perform an act that does not yield profit.
We are willing to give $50 if we receive $100 in return. We might also give $80 in return for $100. But if we try to give $101 in return for $100 it is impossible. This modus operandi is true not only with money or an act toward others, but for anything, as Baal HaSulam explained it:
It is well known to researchers of Nature that one cannot perform even the slightest movement without motivation, without somehow benefiting oneself. When, for example, one moves one’s hand from the chair to the table, it is because one thinks that by putting the hand on the table will be more enjoyable. If he did not think so, he would leave his hand on the chair for the rest of his life without moving it at all. It is all the more so with greater efforts.
Baal HaSulam, “The Peace”
Even people who assist other people more than most, such as volunteers at hospitals or elsewhere, do it only because, at the end of the day, it gives them pleasure.
Baal HaSulam explains that within humanity, there are always up to ten percent “natural born altruists.” Such people respond to others a little differently than most. They sympathize with others and feel their pain as though it were their own, and this feeling compels them to try to help others. Naturally, this altruistic inclination rests on a self-centered basis that requires correction, too, but it is hidden from the eye, as studies in behavioral genetics demonstrate. 
Man’s very essence is only to receive for oneself. By nature, we are unable to do even the smallest thing to benefit others. Instead, when we give to others, we are compelled to expect that in the end, we will receive a worthwhile reward.
Baal HaSulam, “A Speech for the Completion of The Zohar”
When a baby is born, it begins to hear, to see, and to react. It learns and develops from examples that we present to it.
If we left the baby to grow in the woods, it would imitate the animals and grow like an animal. With the exception of a few instincts and reflexes, everything about us comes from learning.
Can we learn the upper system in the same way if we do not feel it? How can we be like that baby, or even a drop of semen that only wishes to be born into a new quality called “giving”?
In other words, a human infant evolves out of a drop of corporeal semen. It learns from examples and eventually becomes a grownup. And now, a drop of spiritual seed, called “the point in the heart,” appears in that person, a new desire—to know what he or she is living for, to reach what exists beyond life, the force that affects us and operates us. In corporeal growth, the ego develops and the quality of reception for oneself becomes improved. In the process of spiritual growth, the quality of giving develops in us.
So what do we need in order to commence the process? We need examples—spiritual teachers. This is why The Book of Zohar was written. Just as children stare with eyes wide open and jaws dropped, craving to devour the world and learn all about it, we should approach The Book of Zohar, which provides us with examples of the quality of giving.
The more we learn how to give, the more we will resemble Nature’s comprehensive power, the power of love and giving. In Kabbalah terminology, it is called “equivalence of form,” which is a gradual process that leads to our sensing Nature’s overall force to the extent that we become similar to it.
 Changing certain gene sequences affects a person’s ability to be good to others, Prof. Ebstein and a team of researchers in behavioral genetics discovered. The researchers assume that there is an immediate reward for altruistic behavior in the form of a chemical called “dopamine,” released in the benefactor’s brain and prompting a pleasant feeling.
M. R. Bachner, I. Gritsenko, L. Nemanov, A. H. Zohar, C. Dina & R. P. Ebstein, “Dopaminergic Polymorphisms Associated with Self-Report Measures of Human Altruism: A Fresh Phenotype for the Dopamine D4 Receptor”, Molecular Psychiatry10 (4), April 2005, pp. 333-335