The foundation of something - the twelve tone scale of Western music, the concrete piers on which an office building stands, a charitable organization that works for a good cause, or even (as Rabbi Min Kantrowitz points out) the base layer for women's face makeup - all of these examples reveal "foundation" to be, in her felicitous rendering, "the basis of something, a necessary aspect without which the rest of the system... would not stand."
Look at the "Tree Of Life" chart of the Sefirot to the left. You'll see that Yesod, Foundation, functions as a kind of funnel. It is the central focus point through which the upper 8 Sefirot (upper 5 if we only count the ones we've been dealing with during the Omer count) are channeled into Malchut, the Sefirah which is most immediate to our world and experience.
Yesod is also the solid foundation of our spiritual explorations and aspirations. It is a firm platform from which to explore and grow. 
Looking at the chart of the Sefirot mapped to the parts of the human body (which we last encountered on Day 20) we see that Yesod is associated with the genitals.

Sexuality is foundational. It is a force which drives not only procreation and preservation of our human species. It is also one of the most powerful forces that can be mustered in the service of deep joy and abiding love. And like anything powerful, it can be turned to ends which are ultimately self-serving, degrading, cruel and/or manipulative.
There are many ways of considering the Lovingkindness in Foundation. But in our media culture which so often commodifies sexuality, perhaps this is a good opportunity to consider the lovingkindness which can be expressed through sexuality at its most sacred, as part of a loving and committed relationship.

Your thoughts?

SF

Tags: Hesed, Yesod