“The use of self control is like the use of brakes on train. It is useful when you find yourself in wrong direction but merely harmful when the direction is right”

Letter to Larry Callen (14 July 1958), p. 133
1990s, The Proud Highway : The Fear and Loathing Letters Volume I (1997)
Context: I find that by putting things in writing I can understand them and see them a little more objectively. … For words are merely tools and if you use the right ones you can actually put even your life in order, if you don't lie to yourself and use the wrong words.

"Cromwell and Noble".
Imaginary Conversations (1824-1829)

Part 6 “The Caucus Race”, chapter 20 (p. 364)
Iron Council (2004)

Source: Beatdom #11: The Nature Issue

Article http://books.google.com/books?id=lHnjAAAAMAAJ&q=%22Remember+that+there+is+always+a+limit+to+self-indulgence+but+none+to+self-restraint+and+let+us+daily+progress+in+that+direction%22 in Young India (2 February 1928, Volume 10, Page 35)
Posthumous publications (1950s and later)

Source: The Queen of the Damned

Source: The Perpetual Calendar of Inspiration

The Elegant Universe : Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory (1999), p. 271
Context: Physicists are more like avant-garde composers, willing to bend traditional rules and brush the edge of acceptability in the search for solutions. Mathematicians are more like classical composers, typically working within a much tighter framework, reluctant to go to the next step until all previous ones have been established with due rigor. Each approach has its advantages as well as drawbacks; each provides a unique outlet for creative discovery. Like modern and classical music, it’s not that one approach is right and the other wrong – the methods one chooses to use are largely a matter of taste and training.

Source: The Adventures of Huckleberry Finn