O disclose Thy lovely face. C. Wesley. [Pardon desired.] There are two centos in common use, each beginning with this line, as follows:—
(1) The first is No. 156 of the Wesleyan Hymn Book, prior to the 1875 revision. It is thus composed: stanza i. is stanza ii. of C. Wesley's hymn, "Lord, how long, how long shall I," which appeared in the Hymns & Sacred Poems, 1740; and stanza ii. and iii. are stanza ii., iii. of "Christ, Whose glory fills the skies". In this form the cento was given in the Wesleyan Hymn Book, 1780, and is found in several Methodist collections. (2) The second form of the hymn is No. 156, in the revised Wesleyan Hymn Book, 1875. It is composed of stanzas ii., iii., and v. of "Lord, how long, how long shall I?" as above.
--John Julian, Dictionary of Hymnology (1907)