Once Thou didst on earth appear. C. Wesley. [God manifest in the Flesh.] This is a cento thus composed: stanza i. from Short Hymns, 1762, vol. ii., No. 790; stanzas ii., iii., Short Hymns , vol. ii., No. 649; and stanza iv., Hymns for Families, 1747, No. 28. In this form it was given in the Wesleyan Hymn Book 1780, No. 401, and from thence has passed into several collections in Great Britain and America. In the 1875 edition of the Wesleyan Hymn Book, stanza iv. is omitted.
--John Julian, Dictionary of Hymnology (1907)