"Unless Hashem builds the house"
Rabbi Elazar opens a discussion of, "A song of ascents for Solomon. Unless the Creator builds the house, they who build it labor in vain; unless the Creator keeps the city, the watchman stays awake in vain." He then comments that King David said this for his son, Solomon, when Nathan the prophet foretold that Solomon would build the Holy Temple. Another explanation of the verse, we learn, is that unless the King, who is Binah, builds the house with the seven pillars of Chesed, Gvurah, Tiferet, Netzach, Hod, Yesod and Malchut of Zeir Anpin, they who build it shall labor in vain. The tabernacle can only be guarded by a youth, who was first Joshua (in the youthful aspect of Metatron), then the child Samuel. God alone guards the Holy Temple, and He guards the righteous as they travel, as it is written, "The Creator shall preserve your going out and your coming in."
In effect, Rabbi Elazar's discourse concerns how to draw the Light of the Creator to our own homes. King David, we are told, composed verses that spoke of the necessity of having the Creator's Light imbued at the seed level of the building of the Temple. Otherwise, all the construction and safeguards would be for naught. For us, this means that our own temples, our homes and communities, must be imbued with this Light. Otherwise, there is no chance for protection and blessing, regardless of what we might do on a physical level.
Without our constant awareness of this need for Light, we are left vulnerable to the forces of chaos. Here we travel back to the seed level of our homes, our communities, and the entire world, and we inject them with the awesome Light of the Creator. The radiance banishes all the darkness and forces of chaos that have wreaked havoc upon our lives since the dawn of humanity.