Rabash, Shlavei HaSulam, “What is the Prohibition to Bless On An Empty Table in the Work”: One has to supply empty vessels so that the Creator could fill them with the upper abundance. This is called a “blessing.”
The spiritual path contains several stages, during which we learn how to properly combine, put together, all parts of reality. What desire do we need to prepare time after time so as to turn to the Creator with various demands: How do we find the means, manifest the attributes, and uncover our unity?
After all, we find that everything has already been prepared for us and is just waiting for our desire. Discoveries that we are making along the way only seem such to us. We call them stages of attainment, but in reality all spiritual degrees already exist, and all the states, including the final one, are predetermined.
Thus, by climbing the rungs of the ladder, coming back from the darkness and separation, and increasingly attaining the overall reality of the universe, we reveal reality only to ourselves. All the new attributes, details, ties, conjunctions, and parts are the manifestations of a new reality that protrudes in front of us out of darkness of concealment.
As a result, when a person sees what the Creator has prepared for him, he “blesses.” But that’s on condition that he feels what he has received in his new attributes. Having started from spiritual oblivion, he began to collect himself at the still, vegetative, and animal levels and was finally born into the light, each time combining two parts: a receiving desire and the attribute of bestowal which rules over him.
This is how one is moving forward: The two components, desire and intention, come to him from Above, and he just precedes them with his demand for them to be revealed, united, and fulfilled. All of that is coupled with a search for the aspiration to bestow in everything that goes beyond his “beastly,” material life.
However, wishing for bestowal isn’t enough; a person needs to receive for the sake of bestowal. This state is called “complete faith.” Until then a person has no opportunity “to bless” because he hasn’t yet received a blessing from the Creator. During the stages of correction the vessels (Kelim) are filled with the Light of Hassadim (Mercy), and then the Light of Hochma (Wisdom) clothes into them. Only then does one come to a blessing.
From the 1st part of the Daily Kabbalah Lesson 1/13/2011, ““What is the Prohibition to Bless On An Empty Table in the Work”