There are depths in man that go the length of lowest Hell, as there are heights that reach highest Heaven; — for are not both Heaven and Hell made out of him, made by him, everlasting Miracle and Mystery as he is?

Thomas Carlyle (1795-1881) Scottish essayist and historian

The French Revolution: A History, Part 3, Book 1, ch. 4 (3.1.4) (1837)
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Regarding the events of 2 September 1792, and the Commune-ordered massacres of prisoners in the Paris prisons.

This passage was popularized in a slightly paraphrased form in Tryon Edwards, ed., A Dictionary of Thoughts (1891):

There are depths in man that go to the lowest hell, and heights that reach the highest heaven, for are not both heaven and hell made out of him, everlasting miracle and mystery that he is.

The Edwards version was, in turn, quoted by Martin Luther King, Jr. in his Detroit sermon "The Christian Doctrine of Man" (1958-02-12).