The First Temple was built in 950 B.C. by King Solomon. The Temple is a symbol of the corrected Kli, the human soul, which is completely directed toward the Creator and is in full contact with Him.
Question: What is the difference between Jerusalem and the Temple?
Answer: A temple is already a more embodied striving toward the Creator because it is located in the city and on the mountain and it means the place of contact between the physical and the spiritual.
The construction of the First Temple represented the unification of the 12 tribes. Then this structure was destroyed and the Second Temple became a symbol of the unity of only two of the tribes.
The Third Temple, as stated in Kabbalistic sources, is the unification of all mankind when all the properties of a person will be striving toward the work of bestowal.
From KabTV’s “Spiritual States” 2/22/22