This is a setting of the evening hymn from compline – the last service of the monastic day, asking for protection during the night. It is in three verses.
Jeremy Summerly:
Thomas Tallis wrote two settings of the compline hymn Te lucis ante terminum, both of which were published in the 1575 Cantiones sacrae. This first setting—like the second—sets only the middle of the three verses in polyphony. The treble part replicates the pitches of the pre-existent chant melody note for note (with the addition of a single ornamental leading note at the final cadence) in a lilting triple-time rhythm, and the accompanying harmonization is a model of economy and placid beauty, nowhere more so than at the delicately handled Picardian cadence at the end of the third phrase.
https://www.hyperion-records.co.uk/dw.asp?dc=W2980_GBAJY9040009
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