from the Oheiv Yisrael by Rabbi Avraham Yehoshua Heshel
|Adam originally included both male and female.|
And the Lord G‑d caused a deep sleep to fall upon the man, and he slept, and He took one of his sides, and closed the flesh in its place…[And He made it into a woman] and brought her to the man. (Gen. 2:21)
It is known that Adam was the epitome of all creation, the handiwork of G‑d Himself. He included all holiness and all the souls of Israel. The entire side of holiness was connected to him and included in him.
Also, Adam originally included both male and female, since he was created with the two [connected] bodies.Everything in the world must contain the concept of both male and female…
Everything in the world must contain the concept of both male and female. This is especially true in serving G‑d, where the male and female elements correspond respectively to “remember” and “keep” [referring to Shabbat].
The essence of the male and female elements respectively is the concept of giving and receiving. Thus, for example, a person can attain great attachment, holiness, and purity of thought. Such a person then gives spiritual delight to the supernal Lights, universes, and attributes. This is the concept of the male element.
At the same time, however, this person receives spiritual sustenance from the supernal universes. This is the concept of his female element. All Israel also partake of this female element when this sustenance is transmitted to them, providing them with everything they need. From it they receive “children, life and food”, and the like.The Male and Female essences come together to once again give birth through the transmission of love to the world…
The concept on high that bestows spiritual sustenance is the Male Essence. The spiritual flux becomes the semen, and the Male and Female essences come together to once again give birth through the transmission of love to the world. Besides its immediate effect, each deed also affects future generations. The deed is then aroused, giving birth to another spiritual flux at that future date [such as on anniversaries].
It is thus written, “And He took one of his sides”; this means that the side and concept of femininity was taken from Adam. He then “closed the flesh in its place”; G‑d put in its place a concept of the physical. According to this concept, the tzadikhas the power to accept the supernal flux and transmit all kinds of good from on high to the lower world. He can even transmit this to the physical.
As taken from, http://www.chabad.org/kabbalah/article_cdo/aid/380616/jewish/The-Female-Aspect-of-Adam.htm