“Everybody gets told to write about what they know. The trouble with many of us is that at the earlier stages of life we think we know everything- or to put it more usefully, we are often unaware of the scope and structure of our ignorance.”

Wasting Time.
Song lyrics, On and On (2003)

Variant translation: The more we learn about the world, and the deeper our learning, the more conscious, clear, and well-defined will be our knowledge of what we do not know, our knowledge of our ignorance. The main source of our ignorance lies in the fact that our knowledge can only be finite, while our ignorance must necessarily be infinite.
Conjectures and Refutations: The Growth of Scientific Knowledge (1963)
Context: The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance. For this, indeed, is the main source of our ignorance — the fact that our knowledge can be only finite, while our ignorance must necessarily be infinite.

Source: Four Seasons in Rome: On Twins, Insomnia, and the Biggest Funeral in the History of the World

Talking about Kabbalah http://www.thelpa.com/lpa/quotes.html

Source: Diary

Hermann Bondi, Assumption and Myth in Physical Theory, (1967) p. 11

Source: Everything Belongs: The Gift of Contemplative Prayer (1999), p. 110

Rich Dad Poor Dad: What the Rich Teach Their Kids About Money-That the Poor and the Middle Class Do Not!