WC maintains that JS taught plural marriage was essential to exaltation.
"Statement of William Clayton," Women's Exponent 15 (June 1, 1886): 2
From him, I learned that the doctrine of plural and celestial marriage is the most holy and important doctrine ever revealed to man on the earth, and without obedience to that principle no man can ever attain to the fulness of exaltation in celestial glory.
(Signed) WILLIAM CLAYTON.
Salt Lake City, February 16, 1874.