Flow of blessing
Indented words are excerpts taken from www.jewishsexuality.com
The week of Yesod in the Sefirat HaOmer corresponds to the rectification of the holy bris. Today is Malchus She'biyesod. "Malchus" is the all-inclusive day, which is the highlight and culmination of the week of "Yesod".
Like all of the other commandments, Sefirat HaOmer is loaded with Kabbalistic significance. Without the Kabbalah, we would not know what we were doing when we put on tefillin, wave the lulav, or blow the shofar on Rosh Hashanah.
Yes, there are simple explanations, but someone who only familiarizes himself with pashat, or simple understandings, resembles a swimmer who is afraid to put on a mask and stick his face in the water. If you tell him there is a whole beautiful, marine world below the surface, teeming with all forms of life, he won't believe you because he has never experienced this deeper, inner world for himself.
When it comes to Sefirat HaOmer, look in your prayer books. At least in the major league prayer books in Israel, you will see adjacent to each day of the counting, two mystical words like Hesed of Hesed, Tiferet of Gevorah, or Hod of Tiferet. These words are from the Kabbalistic world of the Sefirot (channels of spiritual blessing).
Each day of the counting, we are called upon to rectify another sefirah. This is an integral part of the process of inner purification that we are to undergo as we approach the holiday of Shavuot (Feast of Weeks). We are not only to mention the day, but also to undertake the detailed, laborious toil of perfecting our character traits and the channels of celestial blessing that are directly parallel to them, just as a marionette puppet is connected to the hand above, or just like the keys of a piano are connected to the chords inside the piano's lid. Each time a key is hit, a different sound is produced. So too, each time we improve a character trait, a channel of blessing is cleansed in the spiritual worlds above, releasing a flow of blessing to our world below.
Today, Malchus She'biyesod, is an especially auspicious time to take upon ourselves more stringency in sexual purity, in preparation for the giving of the Torah!
For example, one may take upon himself to immerse in a Mikva every time he has a seminal emission. This is known to be a big Segulah for Shmiras Habris. For more on Mikva'os, see here.
Below is a picture of the holy Tzadik Yesod Olam, Rav Shlomo From Zevil, whose Yartzeit was yesterday, Yesod she'beYesod. He worked his whole life on the aspect of family purity amongst Yidden, and with his own hands and at his own expense he built countless Mikva'os in Eretz Yisrael.
In his merit, may we all be Zoche to true Kedusha and Tahara!