As one of Joseph Smith’s largest revelations, Doctrine and Covenants, Section 88 (or, as Joseph Smith called it, “the Olieve leaf which we have plucked from the tree of Paradise”) has a lot of different talking points. As historian Richard Lyman Bushman wrote: “Nothing in nineteenth-century literature resembles it. … The ‘Olive Leaf’ runs from the cosmological to the practical, from a description of angels blowing their trumpets to instructions for starting a school. Yet the pieces blend together into a cohesive compound of cosmology and eschatology united by the attempt to link the quotidian world of the now to the world beyond.” The majority of this Olive Leaf revelation was recorded on 27-28 December 1832, with the end section being recorded as a separate revelation on 3 January 1833 that became so closely associated with the December revelation that they were eventually combined into one document. Among the topics that moved beyond the mundane world of the now is a metaphysical discussion towards the beginning of the December revelation about Jesus the Christ and light.
This portion that discusses Jesus and light has given rise to the idea of an interesting entity in Latter-day Saint through—the light of Christ or Spirit of Christ. The revelation states that: “I now send upon you another comfortor, even upon you my friends; that it may abide in your hearts, even the holy spirit of promise. … This comfortor is the promise which I give unto you of eternal life; even the glory of the celestial kingdom, which glory is that of the church of the first born; even of God. the holiest of all; through Jesus Christ, his son.” After stating that this comforter is given—the promise of eternal life through Jesus Christ—the text then goes into a description of the Christ: “he that assended up on high, as also he, decended below all things; in that he comprehended all things, that he might be in all, and through all things; the light of truth, therefore which <?truth?> shineth— this is the light of Christ.” This light of truth, or light of Christ:
is in the s?n, and the light of the son [sun], and the power thereof by which it was made, as also he is in the moon, & is, the light of the moon, and the power thereof, by which it was made, as also the light of the stars, and the power thereof; by which they were made; and the earth also, and and the power thereof, even the earth upon which you stand, and the light which now shineth; which giveth you light, is through him which enlightneth your eyes; which is the same light that quickneth your understandings, which light, [p. 34] procedeth forth from the presence of God; to fill the emencity of space; the light which is in all things which giveth life to all things, which is the law by which all things are govorned, even the power of God, who sitteth upon his throne; who is in the bosom of eternity, who is in the midst of all things
It seems that the revelation built upon earlier imagery that depicts Jesus lighting the way to salvation to describe the light of Christ as a radiant energy or a form of the glory of God, proceeding from His presence and giving life and intelligence to all creation.
The phrase “the light of Christ” only appears in two other places in Joseph Smith’s corpus, both in the Book of Mormon. The first comes in the Book of Alma where, after discussing a group of Lamanites who converted to Nephite Christianity due to the efforts of Nephite missionaries, the author observes that: “& thus we see the great call of the diligence of men to labour in the vineyards of the Lord & thus we see the great reason of sorrow & also of rejoicing sorrow because of death & destruction among men & joy because of the light of Christ unto life.” Here, the “light of Christ unto life” seems to be used more in the sense of Jesus lighting the way to salvation. The other appearance, in the Book of Moroni, seems to describe something similar:
brethren it is given unto you to judge that ye may know good from evil & the way to judge is as plain that ye may know with a perfect knowledge as the day light is from the dark night for behold the spirit of Christ is given to every man that they may know good from evil. … & now my brethren seeing that ye know the light by which ye may judge which light is the light of Christ see that ye do not judge wrongfully for with that same judgment which ye judge ye shall also be judged wherefore I beseach of you brethren that ye should search diligently in the light of Christ that ye may know good from evil & if ye will lay hold upon every good thing & condemn it not ye certainly will be a child of Christ.
This light of Christ is a source of spiritual illumination that allows people to know good from evil, leading them to become children of Christ in these texts.
Combining these statements in the Book of Mormon (especially the Moroni one) with the Olive Leaf revelation’s reflection has given rise to a specific understanding of the light of Christ in the Church today, but the path to that understanding has taken time. In early days of the Church, the light of Christ seems to have been viewed as synonymous with the Holy Ghost or the Gospel (the latter in the sense of walking in the light of Christ in how one lives their life). This was possible because the Holy Ghost was viewed as some sort of omnipresent force or entity. For example, in the Lectures on Faith (published in 1835 as the original doctrine portion of the Doctrine and Covenants where it remained until the 1920s), Jesus and God the Father are the “two personages who constitute the great matchless, governing and supreme power over all things,” connected because they possess “the same mind … which mind is the Holy Spirit.” As Vern G. Swanson summarized: “The Holy Ghost in this binitarian understanding was the ‘mind’ or common essence, the ‘Spirit of God’ and the ‘Light of Christ,’ emanating from the Father and Son. Most literature from this early period emphasized the ‘influence,’’power,’ ‘fire,’ ‘spirit,’ and ‘gifts’ of the Holy Ghost. It was something to be ‘spread,’ ‘filled,’ ‘poured,’ or ‘bestowed’ upon the righteous, especially after baptism.” Rather than being a personage in the Godhood, the Holy Ghost was a power or mind that connected all creation to God.
While Joseph Smith would teach later in life that the Holy Spirit was a personage, these earlier teachings about the Holy Ghost remained influential in the Church of Jesus Christ of Latter-day Saints throughout the 19th century into the early 20th century. For example, in 1857, President Brigham Young stated that “I do not wish you to understand that the Holy Ghost is a personage having a tabernacle like the Father and the Son; but he is God’s messenger that diffuses his influence through all the works of the Almighty.” Likewise, Elder Parley P. Pratt wrote in 1855 that:
It is … an absolute impossibility for God the Father, or Jesus Christ, to be everywhere personally present.
The omnipresence of God must therefore be understood in some other way than of His bodily or personal presence.
This leads to the investigation of that substance called the Holy Spirit. …
There are several … subtle, invisible substance but little understood as yet by man, and their existence is only demonstrated by their effects. …
The purest, most refined and subtle of all these substances, and the one least understood, or even recognized, by the less informed among mankind, is that substance called the Holy Spirit.
The Holy Ghost was frequently spoken of as a substance that could diffuse influence rather than a personage.
This ran contrary, however, to the teachings of Joseph Smith in the 1840s. For example, in April 1843, he taught that: “The Father has a body of flesh & bones as tangible as mans the Son also, but the Holy Ghost is a personage of spirit.— and a person cannot have the personage <?of the H G. [Holy Ghost]?> in his heart he may recive the gift of the holy Ghost. it may descend upon him but not to tarry with him.” Or, as recorded in another account: “The Holy Ghost is a personage, and a person cannot have the personage of the H. G. in his heart. A man may receive the gifts of the H. G, and the H. G. may descend upon a man but not to tarry with him.” By the time this was published in an official history in 1856, this was edited to match more closely to what Brigham Young and Parley Pratt were teaching, reading similar to how it reads in the Doctrine and Covenants today: “The Father has a body of flesh and bones as tangible as man’s; the Son also: but the Holy Ghost has not a body of flesh and bones, but is a personage of Spirit: were it not so, the Holy Ghost could not dwell in us. A man may receive the Holy Ghost, and it may descend upon him and not tarry with him.” The difference was in the detail of whether or not the Holy Ghost can dwell in our hearts—in the original, He was a personage and thus could not dwell in hearts, while in the latter He was a spirit and thus could. In any case, when this was officially added to the Doctrine and Covenants in 1879, it began to shift the understanding of the Holy Ghost as a substance to understanding the Spirit as a person.
This shift began to show in the writings of Latter-day Saint theologians of the turn of the 20th century. Elder B. H. Roberts wrote in the 1901 edition of his book The Gospel:
In some of the writings of the early Elders of The Church, the fact of the personality of the Holy Ghost was not sufficiently emphasized. In some passages of their writings, indeed, it would almost seem that the Holy Ghost was not regarded as a personage at all; but, mistaking the manifestation of his universal influence for himself, they speak of him as a universally diffused substance, such as electricity or ether. … The Holy Ghost, however, according to the word of God is a personage of spirit, and as such has the limitations of all persons or individuals; but he is possessed of an influence universally diffused and operates as the very power of God.
This reflects the shift in discourse to viewing the Holy Spirit as a person.
This began to cause a separation between the Holy Spirit and the Light of Christ in our theology. As mentioned by Roberts in pointing out the “limitations of all persons,” the corporeal nature of God limits His omnipresence in Mormon thought (since a body exists in a specific portion of space), and the Holy Spirit was seen as the omnipresent part of the Godhead. As the Spirit began to be viewed as a personage as well, that same limitation on omnipresence began to apply to the Holy Ghost, so the idea of the Light of Christ began to fill the omnipresent role for Latter-day Saints. As Elder LeGrand Richards would point out in his influential A Marvelous Work and a Wonder: “Since the Holy Ghost is a personage of spirit in the form of man (See I Nephi 11:11) and hence confined in his personage to a limited space, the question is often asked: How can he be a comforter to all who have received the laying on of hands for the gift of the Holy Ghost, scattered as they may be, among all nations of men?” This necessitated some shifts in how we talked about various aspects of the Holy Ghost and related doctrines.
It took time to separate out the Holy Ghost from the Spirit or Light of Christ. In 1902, for example, President Joseph F. Smith taught that: “Is there any difference between the Spirit of the Lord and the Holy Ghost? The terms are frequently used synonymously. … The Holy Ghost is a personage in the Godhead, and is not that which lighteth every man that cometh into the world. It is the Spirit of God which proceeds through Christ to the world that enlightens every man that comes into the world.” Throughout at least the 1920s, the Holy Ghost and the Light of Christ were used interchangeably, but Joseph F. Smith’s son, Elder Joseph Fielding Smith would begin to differentiate between them more clearly by at least the 1930s. For example, in a personal correspondence, he wrote that: “The Holy Ghost should not be confused with the Spirit which fills the immensity of space and which is everywhere present. This other Spirit is impersonal and has no size, nor dimension; it proceeds forth from the presence of the Father and the Son and is in all things. We should speak of the Holy Ghost as a personage as ‘he’ and this other Spirit as ‘it.’” He also stated that while many terms use to referred to the Holy Ghost “largely are used in relation to the Spirit of Jesus Christ, also called the Light of Truth, Light of Christ, Spirit of God, and Spirit of the Lord; and yet they are separate and distinct things.” Taking his cue from this, in 1948, McConkie stated in general conference that: “[God] has given us the … Light of Christ, and also the Holy Ghost,” indicating that the two entities were separate things. This reflects a somewhat messy and slow process of differentiating between terms for the Light of Christ and terms for the Holy Spirit as they began to be seen as two different things.
This differentiation was partially enabled by utilizing a particular scientific theory of that era, the luminiferous aether. Rather than being an angry sludge sort of thing, this aether was based on the idea that if sound moves through air by waves of vibration of particles in the air passing on to neighboring particles, then things like light that don’t seem to pass through matter must be passing through some other substance. The aether, then, was speculated as being this medium or substance that light passes through. While this was later disproved in scientific circles, it was a relatively popular in Mormon thought to equate the luminiferous aether with the light or spirit of Christ for a while. For example, Elder B. H. Roberts wrote that: “From the presence of these Divine Beings proceeds an essence or substance (perhaps like unto ether) variously called ‘spirit,’ ‘light,’ ‘light of truth,’ ‘light of Christ,’ … through which the purposes of the Divine Intelligence are impressed upon other minds and also upon matter, and hence the orderly creations and their maintenance—the cosmos.” Likewise, Elder John A. Widtsoe quoted Section 88 and explained that: “This quotation gives undoubted evidence of the prophet’s belief that space if filled with some substance which bears important relations to all natural phenomena.” He went on to explain his belief that: “Joseph Smith taught in clearness the doctrine that a subtle form of matter, call it ether or Holy Spirit, pervades all space.” While specifically connected to the Holy Spirit in that last instance, this foreshadowed some aspects of the role of the Light of Christ in the Church today.
There are echoes of this idea of the Light of Christ being an aether for the influence or glory of God still discussed from time to time. For example, in 1966, Elder William J. Critchlow, Jr. taught that: “Again, like the Father and the Son, the Holy Ghost can only be in one place at a time, and he cannot transform himself into any other form or image. To affirm omnipresence of the personage of the Holy Ghost overstates divine purpose. However, his power and intelligence are omnipresent in perhaps the same way the light of Christ fills the immensity of space and is everywhere present. Who can affirm that the two are not in some way correlated agencies or powers through which the Holy Ghost, in administering his affairs, sends forth his gifts?” Similarly, in Elder Bruce R. McConkie’s last book, he wrote that: “It is … the agency used by the Holy Ghost to manifest truth and dispense spiritual gifts to many people at one and the same time. For instance, it is as though the Holy Ghost, who is a personage of spirit, was broadcasting all truth throughout the whole universe all the time, using the light of Christ as the agency by which the message is delivered. … It is in this way that the person of the Holy Ghost makes his influence felt in the heart of every righteous person at the same time.” The idea of the Light of Christ functioning as the media for transmitting the influence of the Holy Ghost seems to be rooted in ideas expressed about the spirit of Christ as a universal aethar.
Today, the Light of Christ has definitions still very much connected to the process of separation from the Holy Ghost. For example, in True to the Faith, a topical reference that the Church publishes, it is defined as follows:
This power is an influence for good in the lives of all people. … In the scriptures, the Light of Christ is sometimes called the Spirit of the Lord, the Spirit of God, the Spirit of Christ, or the Light of Life.
The Light of Christ should not be confused with the Holy Ghost. It is not a personage, as the Holy Ghost is. Its influence leads people to find the true gospel, be baptized, and receive the gift of the Holy Ghost (see John 12:46; Alma 26:14–15).
Conscience is a manifestation of the Light of Christ, enabling us to judge good from evil.
The careful definition of terms used to describe the light and the statement that it should not be confused with the Holy Ghost are an ongoing reflection of the fact that the term “The Light of Christ,” drawing on the language of the Book of Mormon and the Olive Leaf revelation, was effectively synonymous with the Holy Ghost. This was partially because of the ascendancy of the Lectures of Faith in the Doctrine of Covenants in the 1800s and the teachings of important Church leaders, but the incorporation of later teachings of Joseph Smith in Section 130 in the late 1800s initiated a gradual separation in the two terms that took hold most firmly in the mid-20th century. In many ways, this shift in the 20th century has made it sensible to revert the text of Section 130 to its original form, indicating that the Holy Ghost, as a person, cannot dwell in our hearts, since we tend to teach that it’s the influence of the Holy Ghost, delivered by the power of the Light of Christ, that is actually dwelling in our hearts.
 Richard Lyman Bushman, Joseph Smith: Rough Stone Rolling, First Vintage Books Edition (New York: Vintage Books, 2007), 206.
 “Revelation, 27–28 December 1832 [D&C 88:1–126],” p. 33-34, The Joseph Smith Papers, accessed August 12, 2021, https://www.josephsmithpapers.org/paper-summary/revelation-27-28-december-1832-dc-881-126/2
 “Printer’s Manuscript of the Book of Mormon, circa August 1829–circa January 1830,” p. 243, The Joseph Smith Papers, accessed August 13, 2021, https://www.josephsmithpapers.org/paper-summary/printers-manuscript-of-the-book-of-mormon-circa-august-1829-circa-january-1830/247
 “Printer’s Manuscript of the Book of Mormon, circa August 1829–circa January 1830,” p. 456, The Joseph Smith Papers, accessed August 12, 2021, https://www.josephsmithpapers.org/paper-summary/printers-manuscript-of-the-book-of-mormon-circa-august-1829-circa-january-1830/460
 “Doctrine and Covenants, 1835,” p. 52-54, The Joseph Smith Papers, accessed August 13, 2021, https://www.josephsmithpapers.org/paper-summary/doctrine-and-covenants-1835/60
 Vern G. Swanson, “The Development of the Concept of a Holy Ghost in Mormon Theology,” in Line Upon Line: Essays in Mormon Doctrine, ed. Gary James Bergera (Salt Lake City: Signature Books, 1989), 90-91.
 Journal of Discourses, 6:95.
 Parley P. Pratt, Key to the Science of Theology (Liverpool and London: F. D. Richards and L.D. Saints’ Book Depot, 1855), 38-39, https://contentdm.lib.byu.edu/digital/collection/NCMP1820-1846/id/17243
 “Instruction, 2 April 1843, as Reported by Willard Richards,” p. , The Joseph Smith Papers, accessed August 14, 2021, https://www.josephsmithpapers.org/paper-summary/instruction-2-april-1843-as-reported-by-willard-richards/7
 “Instruction, 2 April 1843, as Reported by William Clayton,” p. 70, The Joseph Smith Papers, accessed August 14, 2021, https://www.josephsmithpapers.org/paper-summary/instruction-2-april-1843-as-reported-by-william-clayton/5
 ““History of Joseph Smith”,” p. 137, The Joseph Smith Papers, accessed August 14, 2021, https://www.josephsmithpapers.org/paper-summary/history-of-joseph-smith/474
 B.H. Roberts, The Gospel: An Exposition of its first principles; and Man’s Relationship to Deity, 3rd ed. (Salt Lake City: Desert News, 1901), vii.
 LeGrand Richards, A Marvelous Work and a Wonder (Salt Lake City: Deseret Book Company, 1953), 103.
 Joseph F. Smith, Gospel Doctrine, 5th edition, pp. 66-68.
 Cited in Joseph Fielding Smith Doctrines of Salvation, ed. Bruce R. McConkie (Salt Lake City: Bookcraft, 1954), 1:49-50.
 Smith, Doctrines of Salvation 1:50.
 Conference Report, October 1948, p.26.
 B. H. Roberts, Comprehensive History of the Church, Vol. 2, Ch. 63, pp. 399-400
 John A. Widtsoe, Joseph Smith As Scientist, (Salt Lake City: The General Board Young Men’s Mutual Improvement Associations, 1908), 24, 27.
 Conference Report, April 1966, p.45
 Bruce R. McConkie, A New Witness for the Articles of Faith (Salt Lake City: Deseret Book, 1985), 70.
 True to the Faith: A Gospel Reference (Salt Lake City: Church of Jesus Christ of Latter-day Saints, 2004), 96, https://www.churchofjesuschrist.org/study/manual/true-to-the-faith/light-of-christ?lang=eng