I love Section 93 (of The Doctrine and Covenants)! It’s filled with wonderful, ennobling truths. I feel closer to heaven and everything that’s real when I read it. Here are some of the things I caught when I studied it again this year:
The core substance in us is intelligence, or the light of truth. This substance cannot be created; it has always existed.
From this substance, God created spirits, or spirit bodies for it. Thus, we became His spirit children. Our very essence, our beginning, is this: light, truth, and intelligence.

Light and truth, or the light of truth, is independent of other forces. It forsakes darkness, evil, and the ‘evil one’. In this sphere of existence – our mortal lives on this earth – we, as bodies containing this light of truth, are able to act for ourselves – to draw to us more light, or to reject it and receive darkness instead.
Good and evil are ‘plainly’ manifested to us, and we choose them freely. This is the power of intelligence, or its independence.
The purpose of our existence (all of it) is to grow in truth and light – that which makes up our core. If we continue receiving grace from our Saviour (who, being filled with truth, embodies it and is known as the Spirit of truth), we will grow in it until we, too, are filled with it. This is the glory of God – the light of truth; intelligence. His purpose is to help all that He has formed from this substance to gain a ‘fullness’ of truth, which glorifies them.
This is our potential, and is why choosing evil/darkness brings a person under condemnation. It’s turning away from all that light and truth lead to; going against one’s own nature towards something unnatural (for us as spirits created of light). But if we use our agency, our power of independent action granted by God in this sphere and our core substance, to keep choosing more light/truth, then that core will grow over time to light every part of us. As dual beings with mortal bodies created of earthly elements (for the purpose of testing), the only way we can actually do this is by accepting the power of Jesus Christ, who is full of truth/light, and shares it with us. Or changes our hearts through the Holy Spirit so that we more willingly choose light over darkness, and let the goodness within us grow.