“Rewards and punishment is the lowest form of education.”

After visiting the Mittelbau-Dora concentration camp in Germany, as quoted in The New York Times (20 April 1980) http://www.nytimes.com/books/98/09/27/specials/lindbergh-jews.html

Variant: Sarcasm is the lowest form of wit, but the highest form of intelligence.

"The Christian Religion" The North American Review, August 1881 http://books.google.com/books?id=OPmfAAAAMAAJ&q=%22There+are+in+nature+neither+rewards+nor+punishments+there+are+consequences%22&pg=PA14#v=onepage http://ebooks.library.cornell.edu/cgi/t/text/pageviewer-idx?c=nora&cc=nora&view=image&seq=121&idno=nora0133-2
Variants:
We must remember that in nature there are neither rewards nor punishments there are consequences. The life and death of Christ do not constitute an atonement. They are worth the example, the moral force, the heroism of benevolence, and in so far as the life of Christ produces emulation in the direction of goodness, it has been of value to mankind.
As published in Some Reasons Why (1895) http://www.infidels.org/library/historical/robert_ingersoll/some_reasons_why.html
In nature, there are neither rewards nor punishments — there are consequences.
Letters and Essays, 3rd Series. Some Reasons Why, viii.
Source: The Christian Religion An Enquiry
Context: There are in nature neither rewards nor punishments — there are consequences. The life of Christ is worth its example, its moral force, its heroism of benevolence.

Source: The Little Big Things: 163 Ways To Pursue Excellence (2010), p. 53.

Source: Liberty A to Z (2004), p. 76

August 22
Debates in the Federal Convention (1787)
Context: Every master of slaves is born a petty tyrant. They bring the judgment of heaven on a Country. As nations can not be rewarded or punished in the next world they must be in this. By an inevitable chain of causes & effects providence punishes national sins, by national calamities.

Steps to an Ecology of Mind (1972)