“There's no system foolproof enough to defeat a sufficiently great fool.”

Source: Mathematicians are useful (1971), p. 1: Machol explains his definition of systems engineering.

[“Loving Your Enemies,” Sermon Delivered at Dexter Avenue Baptist Church, King, Jr., Martin Luther, 1957-11-17, https://kinginstitute.stanford.edu/king-papers/documents/loving-your-enemies-sermon-delivered-dexter-avenue-baptist-church, http://www.webcitation.org/6x5ROMlxu, 2018-02-08]
1950s, Loving Your Enemies (November 1957)

Source: The General in His Labyrinth

Pg 48
Against Method (1975)
Context: Progress was often achieved by a "criticism from the past"… After Aristotle and Ptolemy, the idea that the earth moves - that strange, ancient, and "entirely ridiculous", Pythagorean view was thrown on the rubbish heap of history, only to be revived by Copernicus and to be forged by him into a weapon for the defeat of its defeaters. The Hermetic writings played an important part in this revival, which is still not sufficiently understood, and they were studied with care by the great Newton himself. Such developments are not surprising. No idea is ever examined in all its ramifications and no view is ever given all the chances it deserves. Theories are abandoned and superseded by more fashionable accounts long before they have had an opportunity to show their virtues. Besides, ancient doctrines and "primitive" myths appear strange and nonsensical only because their scientific content is either not known, or is distorted by philologists or anthropologists unfamiliar with the simplest physical, medical or astronomical knowledge.

Lews Therin Telamon
(9 November 2000)
Source: Winter's Heart

Source: A Modern Utopia (1905), Ch. 2, sect. 5

Source: Computer Science as Empirical Inquiry: Symbols and Search (1975), p. 116. This is also called the Church–Turing thesis.