The glory of God is intelligence, or, in other words, light and truth. (D&C 93:36)
Man was also in the beginning with God. Intelligence, or the light of truth, was not created or made, neither indeed can be. (D&C 93:29)
Now the Lord had shown unto me, Abraham, the intelligences that were organized before the world was; and among all these there were many of the noble and great ones; (Abraham 3:22)
I think that when “intelligence” is defined as “light and truth,” we are actually given a fair amount of information. It is almost as if it has a dual nature. Think about the dual nature of light. Is it a wave? Is it a particle? It acts like both, depending on the situation. Might intelligence act like light or like truth, depending on the situation? I have no idea.
Light has energy. What generates this light?
And then the “truth” part of it. Does that mean that there is some kind of encoding and storing of information going on intelligence? And if so, does that mean there’s some kind of inherent sensory aspect? Does that mean there is a discernment aspect too? If truth is knowledge of what is, was, and what will be, how does it know it is eternal and not temporary? That's like saying truth is history and prophesy all rolled into one.
Is truth the message or is it the vessel holding truth? Or is light the vessel that holds truth? How do light and truth become connected? Or are they inseparably connected already?
D&C 130 talks about how intelligence is increased through diligence and obedience.
And if a person gains more knowledge and intelligence in this life through his diligence and obedience than another, he will have so much the advantage in the world to come. (D&C 130:19)
Whatever the exact connective nature of light and truth in intelligence, we are clearly told how to get more. More is good.
Inevitably the question will be asked, “What good is this stuff Joseph Smith gave us about intelligence, light, and truth? I think the basic principles of intelligence can keep us grounded in the midst of dialogues about philosophy, neuroscience, psychology, and other stuff that has to do with brains and being smart. It helps us see beyond the mortal chemical imbalances, genetic defects, developmental delays, and other such problems into the divine potential within.