A person has ten soul powers, three of intellect, and seven of emotion. His intellect and emotion, in their pure state, are completely bound up with the essence of the person, and cannot be separated from him at all. Your memories and feelings cannot be taken away by someone else, and they cannot be (directly) replicated by someone else, they are part of the person himself.
However, a person also has three “garments” for his intellect and emotion, which are the three modes of expression of thought, speech, and action. These three garments are not fully united with the essence as the intellect and emotions are, they can be manipulated or replicated by other people, and are much less “a part of the person himself” than the intellect and emotions.
Yet, the only way we express our intellect and emotions is through these three garments. On the one hand they are less “us,” but on the other hand, they are all we can express about us.
Similarly, as it were, Hashem has Ten Sefiros in Atzilus. These are like His intellect and emotions, at least in terms of how He relates to creations. In their pure state they are absolutely united with Him, having no separate identity whatsoever. However, He expresses His Ten Sefiros to us through His three “garments” called the Sefiros of Beriah, Yetzirah, and Asiya. Beriah is like the garment of thought, Yetzirah like the garment of speech, and Asiya like the garment of action.
Whatever we perceive of Hashem in His “garments” of BY”A will never be the same level of Oneness with Him like the Ten Sefiros as they exist in Atzilus. However, for anyone living outside of Atzilus, which is everyone except Moshe and the Neviim, we only know of Hashem through the garment of the Sefiros of BY”A, and cannot directly access the Torah as it exists in Atzilus. The exception to this was the generation of Moshe, who were elevated to such a level that they could perceive the Torah in its purest state in Atzilus.
However, all generations after that needed the Torah to come down into the level of the Sefiros of BY”A that they were able to perceive. This process required a Navi, with a soul of Atzilus, and with the help of power from Hashem beyond Atzilus, to be able to take Hashem’s Light in the Torah and bring into the level of the Sefiros of BY”A themselves, something normally impossible. Only an infinite power from Hashem who can do all impossible things can transform the Keilim of BY”A to be like the Keilim of Atzilus and be able to unite with His Light in the Torah as though they were still in Atzilus. This is the incredible accomplishment of the prophets, as will be explained.
