The Key to the Knowledge of God

And if your eye be single to my glory, your whole bodies must be filled with light, and there shall be no darkness in you; and that body which is filled with light comprehendeth all things. Therefore, sanctify yourselves that your minds become single to God, and the days will come that you shall see him;for he will unveil his face unto you, and it shall be in his own time, and in his own way, and according to his own will.

Doctrine & Covenants 88:67-8

I never understood this well at all. Single eyes and bodies full of light always sounded like a load of gibberish. It finally started to make sense, though, when I combined it with another scripture I read the other day: For the word of the Lord is truth, and whatsoever is truth is light, and whatsoever is light is Spirit, even the Spirit of Jesus Christ. And the Spirit giveth light to every man that cometh into the world: and the Spirit enlighteneth every man through the world, that hearkeneth to the voice of the Spirit (Doctrine & Covenants 84:45-6).

So the light comes from the Spirit. It's not a very substantial fact by itself, but having made that first connection, I easily thought of the following familiar verses:

• The glory of God is intelligence, or, in other words, light and truth (Doctrine & Covenants 93:36).
• For behold, this is my work and my glory—to bring to pass the immortality and eternal life of man (Moses 1:39).
• And this is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent (John 17:3).

Let's piece these together:

• The Holy Ghost gives us light.
• Light is synonymous with glory and truth.
• Glory is in the eternal life of man.
• Eternal life is to know God.

The sum of these verses is to begin to explain the role of the Holy Ghost in bringing about eternal life. They also add some meaning to Doctrine & Covenants 84:19, which says that the Melchizedek Priesthood holdeth the key of... the knowledge of God. I've occasionally wondered what exactly the Lord means by the key of the knowledge of God, but it now appears that he is referring directly to the key of the bestowal of the gift of the Holy Ghost, which is not otherwise specifically mentioned in his description of the Melchizedek Priesthood.

So it turns out that the gift of the Holy Ghost, as the means to eternal life, is kind of a bigger deal than we might often think. Elder David Bednar was kind enough to neatly summarize this for me:

Praying, studying, gathering, worshipping, serving, and obeying are not isolated and independent items on a lengthy gospel checklist of things to do. Rather, each of these righteous practices is an important element in an overarching spiritual quest to fulfill the mandate to receive the Holy Ghost. The commandments from God we obey and the inspired counsel from Church leaders we follow principally focus upon obtaining the companionship of the Spirit. Fundamentally, all gospel teachings and activities are centered on coming unto Christ by receiving the Holy Ghost in our lives.