So, I found the text of the poem that song (see comments from previous post) is, so YAY! Here they are, in their... early English weird glory. Only imagine it with weird NYARK! EERK! sounds mixed in.

Of a rose singe we,
Misterium mirabile.

This rose is red of colour bright,
Thro whom our joye gan alight
Upon a Christesmasse night,
Claro David germine.

Of this rose was Christy-bore,
To save mankind that was forlore,
And us alle from sinnes sore,
Prophetarum carmine.

This rose, of flowres she is flower;
She ne will fade for no shower;
To sinful men she sent succour,
Mira plenitudine.

This rose is so fair of hue;
In maid Mary that is so true
Y-borne was Lord of virtue,
Salvator sine crimine.