After the Tzimtzum (restriction), the Upper Nine became the place of Kedusha, and Malchut, over which there was the Tzimtzum, became the place of the worlds. And there are two discernments to be made: 1) a vacant place, which is a place for the Klipot, whose essence is the desire to receive only for themselves; and 2) a free place, meaning a place that became free for inserting what one chooses—Kedusha or the opposite.
Had it not been for the Tzimtzum, the whole of reality would have been in the form of Simple Light. Only after the Tzimtzum occurred was there room for choosing to do bad or good.
The bounty extends into that place through choosing the good. And this is the meaning of what is written in the writings of the Ari, that the Light of Ein Sof shines to the lower ones.
Ein Sof is called “the desire to do good to His creations.” And although we discern many worlds, ten Sefirot, and other names, it all extends from the Ein Sof, called “the Thought of Creation.”
The names, Sefira and “world,” are because the abundance that pours off the Ein Sof descends through that Sefira and world. This means that since the lower ones cannot receive His bounty without preparation and correction, in order for the lower ones to be able to receive, corrections were made, by which there was ability to receive. This is called Sefirot.
In other words, each Sefira has its unique correction. Because of that there are many discernments. But they are only with respect to the receivers, since when the lower one receives the abundance from Ein Sof, it receives through a special correction, which adapts it to receive the bounty. This is the meaning of receiving through a special Sefira; although there are no changes whatsoever in the bounty itself.
Now you will understand the matter of the prayer that we pray to the Creator, which is the Light of Ein Sof, being the connection that the Creator has with the creatures, called “His desire to do good to His creations.” And even though there are many names with the aim of the prayer, the interpretation is that the bounty will pour forth through the corrections in the souls. This is because precisely through the corrections in the souls will the abundance be in the hands of the receivers.