(1) From: Daniel W. Patterson, The Shaker Spiritual (Princeton UP, 1979, pp. 372-373):

This song ["Simple Gifts"] gave a title to Edward D. Andrews' pineering study of Shaker songs and a theme to Aaron Copland's ballet suite "Appalachian Spring." These men made it the most widely known of the Shaker spirituals. It also had popularity among the Shakers. More than fifteen manuscripts preserve the tune, and it survives in oral tradition.
The manuscripts identify the song as a Quick Dance, but give conflicting word of its origin. One written at Lebanon says that it was received from a Negro spirit at Canterbury. Andrews reports seeing it described as "composed by the Alfred Ministry June 28, 1848." I have been unable to find his authority, but several manuscripts do record the song from the singing of Elder Joseph Brackett and a company from Alfred, who visited a number of societies in the summer of 1848. In her youth at Hancock, Mrs. Olive H. Austin heard that it was Elder Joseph's own song. Eldress Caroline Helfrich there remembered seeing him sing it in a meeting room, turning about "with his coat tails a-flying."

(2) From: Edward Deming Andrews, The Gift to be Simple: Songs, Dances and Rituals of the American Shakers (1940; Dover, 1962, p. 136):

Like "Come life, Shaker life," this song ["Simple Gifts"] was sung everywhere in the United Society. It appears in many collections copied down during the period of "Mother Ann's Work" (1837-1847 and after) and probably was a product of that revival. One manuscript states that the song was "composed by the Alfred Ministry June 28, 1848." It is a rather lively piece, Shaker Allegro in the original MS.

~Masato