Light and Vessel 5. It is impossible for light to exist in all the worlds without a vessel. The concept of a spiritual vessel is explained in Petiḥa LeḤokhmat HaKabbala, sections 3 and 4. Initially, there was only one vessel in the ten sefirot, which was Malkhut.
When we say that there are five levels, namely, Keter, Ḥokhma, Bina, Tiferet, and Malkhut, all these are all only parts of Malkhut, which is called the fourth level. In other words, these sefirot are defined according to their position in the process of the completion of the vessel, which is the Malkhut that is called the fourth level (as explained in Petiḥa LeḤokhmat HaKabbala, section 5). However, after the first constriction (tzimtzum), a partition was placed upon the vessel of Malkhut, blocking the supernal light from being enclothed in it.
Therefore, when the supernal light reaches the partition, the partition collides with the light and rebuffs it. This collision is referred to as the fusion through collision of the supernal light against the partition upon the vessel of Malkhut. The light that is rebuffed backward is called the “ten sefirot of the returning light,” since the light that is rebuffed ascends from below to above and enclothes the ten sefirot that are in the supernal light, known as the “ten sefirot of the direct light.”
New vessels are formed from this returning light to enclothe the supernal light, replacing Malkhut, which was constricted so that it could not receive light. The content of those new vessels, which are called the “ten sefirot of the returning light,” is explained in Petiḥa LeḤokhmat HaKabbala sections 14–26.