Becoming a spiritual embryo means totally annulling oneself before the Upper One. There is a clear analogy in this world: an embryo cannot choose whether or not to eat, while a baby already can. An embryo receives sustenance directly through an umbilical cord, but it has to receive an anti-egoistic screen to be connected with its mother. Being an embryo is tremendous work. It seems to us that a drop of semen simply grew to 7 pounds in order to be born, but that isn’t completely correct. It not only gained 7 pounds; it also climbed 125 spiritual degrees, as it is written: “In the mother’s womb a candle burns and enables an embryo to see from one end of the world to the other, and it is taught the entire Torah,” the entire Light of Infinity (NRNHY).
An embryo receives and digests only to the degree that it annuls itself before its mother, and this annulment must take place in every spiritual degree until the End of Correction (Gmar Tikkun). A screen is needed so that it will not interfere with the action of the Upper One and so that it will only annul its own ego. It remains a drop of semen until its birth, as it were, while 7 pounds are formed only by annulling itself.
Until you become a drop of semen, you simply do not exist in spirituality. Annul yourself relative to the very first degree of spirituality, annul all your egoism relative to the point in the heart that you received, and then you will become a drop of spiritual semen and enter the mother’s womb of the Upper Partzuf. There, you will see all your friends; they are waiting for you. You are the only one missing in order for the spiritual embryo to start growing and evolving! You cannot do it alone because you have to unite with the others inside one Mother.
From the Daily Kabbalah Lesson 7/9/10, The Study of the Ten Sefirot