The doctrine of baptism for the dead was first made known to the Saints in a discourse by the Prophet at the funeral of Elder Seymour Brunson, August 10, 1840. This doctrine was not understood by him until after the restoration of the keys and the Priesthood of Elijah in the Kirtland Temple, although it had been referred to since the night of the first appearance of Moroni. In this revelation of January, 1841, the Lord revealed greater light regarding this wonderful principle. It was here made known that this ordinance was to be performed in the temple of the Lord. A baptismal font for this purpose was to be placed in the basement of the temple, "as a simile of the grave," and was commanded to be in a place underneath where the living are wont to assemble, to show forth the living and the dead; and that all things may have their likeness, and that they may accord one with another; that which is earthly conforming to that which is heavenly" (Doc. and Cov. Sec. 128:13).
In an epistle to the Twelve Apostles, who were at the time in Europe, President Joseph Smith, October 19, 1840, made the following statement:
"I presume the doctrine of 'baptism for the dead' has ere this reached your ears, and may have raised some inquiries in your minds respecting the same. I cannot in this letter give you all the information you may desire on the subject; but aside from knowledge independent of the Bible, I would say that it was certainly practiced by the ancient churches; and St. Paul endeavors to prove the doctrine of the resurrection from the same, and says, 'Else what shall they do which are baptized for the dead, if the dead rise not at all? Why are they then baptized for the dead?'
"I first mentioned the doctrine in public when preaching the funeral sermon of Brother Seymour Brunson; and have since then given general instructions in the Church on the subject. The Saints have the privilege of being baptized for those of their relatives who are dead, whom they believe would have embraced the Gospel, if they had been privileged with hearing it, and who have received the Gospel in the spirit, through the instrumentality of those who have been commissioned to preach to them while in prison."