Two Excerpts from Joseph Smith concerning the Gathering of Israel

On the Gathering of Israel

"Dear Brethren,

I am happy in being informed by your letter that your mission swells 'larger and larger'; it is a great and important mission, and one that is worthy of those intelligences who surround the throne of Jehovah to be engaged in; Although it appears great at present, yet you have but just begun to realize the greatness, the extent and glory of the same. If there is any thing calculated to interest the mind of the saints, to awaken in them the finest sensibilities; and arouse them to enterprise, and exertion, surely it is the great and precious promises, made by our heavenly Father to the children of Abraham; and those engaged in seeking the outcasts of Israel, and the dispersed of Judah, cannot fail to enjoy the Spirit of the Lord, and have the choicest blessings of Heaven rest upon them in copious effusions. Brethren you are in the path way to Eternal Fame! and immortal Glory; and inasmuch as you feel interested for the covenant people of the Lord, the God of their Father shall bless you." - Letter to Orson Hyde and John E. Page, May 14, 1840,  Joseph Smith, Jr.

On the Effects of the Holy Ghost

"This first Comforter or Holy Ghost has no other effect than pure intelligence. It is more powerful in expanding the mind, enlightening the understanding, and storing the intellect with present knowledge, of a man who is of the literal seed of Abraham, than one that is a Gentile though it may not have half as much visual effect upon his body; for as the Holy Ghost falls upon one of the literal seed of Abraham, it is calm and serene; and his whole soul and body are only exercised by the pure spirit of intelligence; while the effect of the Holy Ghost upon a Gentile, is to purge out the old blood, and make him actually of the seed of Abraham. That man that has none of the blood of Abraham (naturally) must have new creation by the Holy Ghost. (Teachings of the Prophet Joseph Smith, p.149)"