[Rough translation] Also with this, we understand the concept according to רז"ל, that the Ruachs of Tzaddikim, or their Neshamas come and impregnate (Ibur) an Adam, in the secret which is called Ibur, to help him his his avodas Hashem (may He be blessed). And just as it is written in במדרש הנעלם מכתיבת יד, he comes to purify him, and to help him. Rabbi Natan refers to these as the Neshamas of Tzaddikim, which come to help him. And, just as it said at the beginning of Parshat Bereishit in Sefer haZohar, על רב המנונא סבא,שבא אצל ר"א ורבי אבא, כדמות טעין חמרי וכו':