"Intelligence is eternal and exists upon a self-existent principle. It is a spirit from age to age and there is no creation about it." -The King Follett Sermon, Joseph Smith Jr.
2 Ne 2:14
D&C 93:27-36 And no man receiveth a fulness unless he keepeth his commandments. He that keepeth his commandments receiveth truth and light, until he is glorified in truth and knoweth all things. Man was also in the beginning with God. Intelligence, or the light of truth, was not created or made, neither indeed can be. All truth is independent in that sphere in which God has placed it, to act for itself, as all intelligence also; otherwise there is no existence. Behold, here is the agency of man, and here is the condemnation of man; because that which was from the beginning is plainly manifest unto them, and they receive not the light. And every man whose spirit receiveth not the light is under condemnation. For man is spirit. The elements are eternal, and spirit and element, inseparably connected, receive a fulness of joy; And when separated, man cannot receive a fulness of joy. The elements are the tabernacle of God; yea, man is the tabernacle of God, even temples; and whatsoever temple is defiled, God shall destroy that temple.The glory of God is intelligence, or, in other words, light and truth.
After reading some more about what Joseph Smith was taught and taught about creation and matter. There is some interesting stuff here. It seems that Joseph Smith identifies two primordial and eternal substances that on one hand are called light/spirit/intelligence and on the other is element. Both are eternal. Element can be recycled. I don't think intelligence is recycled as there is no reincarnation. The relationship of these things I don't know. Whether one can be converted into the other I don't know. Joseph says element is the substance "in which dwells all the glory". Well the glory of God is intelligence. So again, maybe it is the intelligence/spirit/light that is the eternal part. I thought it interesting that both light and element are required to come together to achieve a fullness of joy.
LDS Doctrine teaches of the eternal nature of the spirit and that all mankind are spirit children of God who is our Heavenly Father. Joseph Smith taught that intelligence or the spirit of man was not created but is self-existent and co-eternal with God. However, beyond this, it is unclear by what mechanism (adoption or gestation) man is considered spirit children of God. This question is like the ultimate nature vs. nurture debate. Recent LDS General Authorites have said that our “intelligence was clothed in spirit bodies.” Brigham Young is quoted as saying, “He created man, as we create our children; for there is no other process ” (JoD 11:122-123). Joseph Smith “But if I am right, I might with boldness proclaim from the house tops that God never did have power to create the spirit of man at all” (Follett).
Whether man is inherently composed of a similar eternal substance as God, man was spiritually gestated and generated by God or both, the philosophical importance of either scenario is the equality and eternal potential of man. Once you start believing that man is a created being not unlike the dungbettle or the ape, it doesn’t take long for some to begin believing that God made them better then others.
There are some out there which may criticize a belief in eternal element or eternal intelligence by appealing to science. Current science claims they have discovered the background radiation thought to be left behind from the Big Bang which scientist believe was a creation of everything out of nothing. Personally, I don't think that LDS need to argue over over the Big Bang because these same scientist are also looking for "dark energy" and "dark matter" which they theorize to make up over 96% of the mass-energy of the Universe. Therefore, if scientists can't even see, measure, or explain 96% of the Universe, then I am sure we have much to learn still about the 4% we can see.