“There are only two ways of telling the complete truth--anonymously and posthumously.”

Aphorism 19
Novum Organum (1620), Book I
Context: There are and can be only two ways of searching into and discovering truth. The one flies from the senses and particulars to the most general axioms, and from these principles, the truth of which it takes for settled and immovable, proceeds to judgment and to the discovery of middle axioms. And this way is now in fashion. The other derives axioms from the senses and particulars, rising by a gradual and unbroken ascent, so that it arrives at the most general axioms last of all. This is the true way, but as yet untried.

The Negro and His Nemesis (1904)

Introduction to the Bhagavad-Gita (1944)

"Great Thought" (19 February 1938), published in The Notebooks of Raymond Chandler (1976)
Context: There are two kinds of truth: the truth that lights the way and the truth that warms the heart. The first of these is science, and the second is art. Neither is independent of the other or more important than the other. Without art, science would be as useless as a pair of high forceps in the hands of a plumber. Without science, art would become a crude mess of folklore and emotional quackery. The truth of art keeps science from becoming inhuman, and the truth of science keeps art from becoming ridiculous.

The source generally (but falsely) cited is Einstein's The World As I See It http://en.wikipedia.org/wiki/The_World_as_I_See_It_(book) (1949). The quotation is probably a translation of "Der Zufall ist das Pseudonym, das der liebe Gott wählt, wenn er inkognito bleiben will" (attributed to Albert Schweitzer).
Disputed

Director's commentary for Dragonfly.

Source: Fire and Hemlock