I have addressed this topic in my books Panim Masbirot and Talmud Eser HaSefirot. I will review the ideas here in brief.
The Creator’s initial intent for the Creation was to bestow benefit on the created beings commensurate with His generosity, may He be blessed and exalted. Therefore, souls were imprinted with the great will and desire to receive His shefa (divine bounty). The will to receive is the vessel that contains the measure of pleasure that is in the shefa, because the measure of greatness and strength of the will to receive the shefa is commensurate with the measure of pleasure and delight in the shefa, no more, no less. They are bound together to such an extent that they cannot be distinguished from one another except in terms of that to which they relate: The pleasure is related to the shefa, while the great will to receive the shefa is related to the created being who receives it. Both of these are necessarily drawn from the Creator, only they must be distinguished in the aforementioned manner: The shefa is drawn from His essence, that is, its existence emanates from His essence yesh miyesh. The will to receive, which is incorporated there, in the shefa, is the root of all created beings, that is, it is the root of any new creation, which constitutes the emergence of existence ex nihilo (yesh me’ayin), since the Creator’s essence certainly does not contain any trace of the will to receive, God forbid.4Since the Creator’s essence does not contain any aspect related to receiving, as He needs nothing from anyone, the will to receive could not emanate from His essence, as the shefa did, but rather had to be created as a totally new entity from nothingness.