The sources are varied epochally and geographically.

It was chilling, epochally sad.

They range from the epochally famous, like Booth (richly played by Michael Cerveris), to the nearly forgotten, like Charles Guiteau (Denis O'Hare), the megalomaniac who shot President James Garfield.

"The Colonial Andes: Tapestries and Silverwork, 1530-1830" at the Metropolitan Museum dramatizes, epochally, the glorious fusion and ruinous collision of native and European cultures that was Nuevo Mundo.

--but hic8ubique's identification of the "(Mother) Church" is also suggestive; if the late-15th c. date is accurate, then this carol could have been shaped by reaction to the same forces destructive to 'Rome' that, slightly later, were represented epochally by Luther: local political-economic autonomy movements; vernacularization of Scripture (and hymning itself!)