“Any sufficiently advanced technology is equivalent to magic.”

Profiles of the Future (revised edition, 1973)
On Clarke's Laws
Source: Profiles of the Future: An Inquiry Into the Limits of the Possible

This is derived from the third of Arthur C. Clarke's three laws : "Any sufficiently advanced technology is indistinguishable from magic." There are other variants which had inverted this including one known as Gehm's corollary http://www-users.cs.york.ac.uk/susan/cyc/l/law.htm, published several years earlier : "Any technology distinguishable from magic is insufficiently advanced." The earliest variant seems to be "Any sufficiently advanced magic is indistinguishable from technology." It has been called "Niven's Law" and attributed to Larry Niven by some, and to Terry Pratchett by others, but without any citation of an original source in either case — the earliest occurrence yet located is an anonymous one in Keystone Folklore (1984) by the Pennsylvania Folklore Society.
Foundation's Fear (1997)

Source: Pushing Ice (2005), Chapter 30 (p. 435)

in his Nobel Lecture http://nobelprize.org/nobel_prizes/physics/laureates/2000/kroemer-lecture.html, Quasi-Electric Fields and Band Offsets: Teaching Electrons New Tricks, 8 December 2000, at Aula Magna, Stockholm University.

Source: PsyberMagick (1995), p. 15

A Case of Need (1968)

Source: Quoted in: Researcher's Close Encounters Convince Him Of Extraterrestrials The Virginian-Pilot, Roy A. Bahls, http://nl.newsbank.com/nl-search/we/Archives?p_product=VP&p_theme=vp&p_action=search&p_maxdocs=200&p_topdoc=1&p_text_direct-0=0EAFF84CB5EACDC1&p_field_direct-0=document_id&p_perpage=10&p_sort=YMD_date:D&s_trackval=GooglePM (22 March 1995)

Remarks by President Obama and Prime Minister Abe of Japan at Hiroshima Peace Memorial at Hiroshima Peace Memorial in Hiroshima, Japan (May 27, 2016) https://www.whitehouse.gov/the-press-office/2016/05/27/remarks-president-obama-and-prime-minister-abe-japan-hiroshima-peace
2016
Context: There are many sites around the world that chronicle this war -- memorials that tell stories of courage and heroism; graves and empty camps that echo of unspeakable depravity. Yet in the image of a mushroom cloud that rose into these skies, we are most starkly reminded of humanity’s core contradiction; how the very spark that marks us as a species -- our thoughts, our imagination, our language, our tool-making, our ability to set ourselves apart from nature and bend it to our will -- those very things also give us the capacity for unmatched destruction. [... ] Science allows us to communicate across the seas and fly above the clouds; to cure disease and understand the cosmos. But those same discoveries can be turned into ever-more efficient killing machines. The wars of the modern age teach this truth. Hiroshima teaches this truth. Technological progress without an equivalent progress in human institutions can doom us. The scientific revolution that led to the splitting of an atom requires a moral revolution, as well.

From Hawking's article A Brief History of Relativity http://www.time.com/time/magazine/article/0,9171,993018-6,00.html, in Time magazine (31 December 1999)