Answer: Love is unity in one common desire. Kabbalah gives us the following example: When Bina reaches the state of Hafetz Hesed (wanting nothing for oneself), it comes down to Malchut, unites with it, and absorbs its desire so as to fulfill it with all the force of Bina.
That’s called love: to absorb someone else’s desire and fill it with whatever you can. It is written that one has to give up his only pillow; it’s the manifestation of love which we need to achieve.
But how is it possible to achieve it? We have to make sure that in the material world each one would have all the basic necessities, and in the spiritual world each one would receive everything there is in our common desire (Kli, vessel).
It’s very important to view all of us as one desire and to do everything to keep it alive. Each one must feel that it depends on him and that it’s in his power to tip the scale for this world from the cup of guilt to the cup of mercy. This way, we create a place called Malchut in which the Upper Light, the Creator, is revealed, but we have to try not to forget that the ultimate goal is to give contentment to the Creator.
But it’s not easy to do it in regards to the Creator; we still lack a clear feeling of His Light. So we should, at least, think about how to bring pleasure to the place where He is hiding, the place all desires for Him have assembled. As it is written, "From the love of the created beings to the love of the Creator." Love of the created beings actually is the most general, unified desire.
The relationship between our souls that we want to restore is called the love of friends. Friends are individuals coming together on the material level in order to reach the inner, spiritual connection. We already know all about it; now it’s the time to just implement it.
An infinite number of words have already been spoken about it, but, each time, they are perceived anew, according to the state a person is in. We only need to absorb them more deeply within ourselves, and the Light will come and develop in a person the entire picture without words. Then it will become clear to us.
Here, patience is needed. It’s not that I agree to wait and put everything away for later, for tomorrow. Have the patience to make every possible effort today, but if you don’t see any signs of success, have confidence that it will happen any moment.
From the Daily Kabbalah Lesson 12/10/2010, Baal HaSulam, Letter 13, 1925