The Latin poem John Gower composed to mark his January 1398 marriage to Agnes Groundolf, Est amor in glosa, presents multiple forms of interpretive difficulty and affords an opportunity to observe the author at work constructing individual lines of poetry. Its variable presentation in manuscripts raises doubts about its extent, whether the poem beginning ‘Est amor in glosa’ and preceded by a Latin headnote ought to be considered to consist of fifteen, nineteen, or twenty-seven lines. 1 Gower’s first great modern editor, G. C. Macaulay, distinguished two poems, incipit ‘Est amor in glosa’ (nineteen lines) and incipit ‘Lex docet auctorum’ (eight lines). 2 In his new edition of Gower’s minor Latin works, R. F. Yeager, following a suggestion of David R. Carlson’s, prints as one poem all twenty-seven lines commonly found in sequence in the manuscripts, subsuming Macaulay’s ‘Lex docet auctorum’ as lines 20–27 of Est amor in glosa...