A very old (1567) piece of religious poetry by the Wedderburn brothers. An all-time favorite of British musicians, it was put into music many times since then. The most striking version is probably the one by Benjamin Britten, who made a breathtaking arrangement of the last two paragraphs. Eerie, out-of-this-world atmosphere, sounds like a fairy queen hymn (I've never heard a fairy queen hymn, and chances are, neither have you, but just trust me: that's exactly what it sounds like). The kind of things you'll remember in the next life.

Full text follows (Middle English purists, please remember that this text has been written by Scotsmen):
    I come to hevin which to tell
    The best nowells that e'er befell
    To you thir tythings trew I bring
    And I will of them say and sing.

    This day to you is born ane child
    Of Marie meik and Virgin mild
    That bliss it bairn bening and kind
    Sall you rejoyce baith hart and mind.

    Lat us rejoyis and be blyth
    And with the Hyrdis go full swyth
    And see what God of his grace hes done
    Throu Christ to bring us to his throne.

    My saull and life stand up and see
    Wha lyis in ane cribbe of tree.
    What Babe is that, sa gude and fair
    It is Christ, God's son and Air.

    O my deir hard, yung Jesus sweit
    Prepair thy creddil in my spreit!
    And I sall rock thee in my hart
    And never mair fra thee depart.

    Bot I sall praise thee evermoir
    With sangis sweit unto thy gloir
    The kneis of my hard sall I bow
    And sing that rycht Balulalow.