“[T]hey are only to be seen and understood by the power of the Holy Spirit, which God bestows on those who love him, and purify themselves before him; To whom he grants this privilege of seeing and knowing for themselves; That through the power and manifestation of the Spirit, while in the flesh, they may be able to bear his presence in the world of glory.” (D&C 76: 116-117.)
“And it shall come to pass, that if the Gentiles shall hearken unto the Lamb of God in that day that he shall manifest himself unto them in word, and also in power, in very deed, unto the taking away of their stumbling blocks.” (1 Ne. 14: 1.)