Not everything that can be counted counts, and not everything that counts can be counted.

From William Bruce Cameron's Informal Sociology: A Casual Introduction to Sociological Thinking (1963), p. 13. The comment is part of a longer paragraph and does not appear in quotations in Cameron's book, and other sources such as The Student's Companion to Sociology (p. 92) attribute the quote to Cameron. A number of recent books claim that Einstein had a sign with these words in his office in Princeton, but until a reliable historical source can be found to support this, skepticism is warranted. The earliest source on Google Books that mentions the quote in association with Einstein and Princeton is Charles A. Garfield's 1986 book Peak Performers: The New Heroes of American Business, in which he wrote on p. 156

Albert Einstein liked to underscore the micro/macro partnership with a remark from Sir George Pickering that he chalked on the blackboard in his office at the Institute for Advanced Studies at Princeton: "Not everything that counts can be counted, and not everything that can be counted counts."