“I find it so difficult to dispose of the few facts which to me are significant, that I hesitate to burden my attention with those which are insignificant, which only a divine mind could illustrate. Such is, for the most part, the news in newspapers and conversation. It is important to preserve the mind's chastity in this respect.”
Life Without Principle (1863)
Context: Not without a slight shudder at the danger, I often perceive how near I had come to admitting into my mind the details of some trivial affair, — the news of the street; and I am astonished to observe how willing men are to lumber their minds with such rubbish, — to permit idle rumors and incidents of the most insignificant kind to intrude on ground which should be sacred to thought. Shall the mind be a public arena, where the affairs of the street and the gossip of the tea-table chiefly are discussed? Or shall it be a quarter of heaven itself, — an hypæthral temple, consecrated to the service of the gods? I find it so difficult to dispose of the few facts which to me are significant, that I hesitate to burden my attention with those which are insignificant, which only a divine mind could illustrate. Such is, for the most part, the news in newspapers and conversation. It is important to preserve the mind's chastity in this respect.
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Henry David Thoreau 385
1817-1862 American poet, essayist, naturalist, and abolitio… 1817–1862Related quotes
MS. Rawl 85 (1588), p. 17. A very similar but anonymous copy is in the British Museum. Additional MS. 15225, p. 85. And there is an imitation in J. Sylvester’s Works, p. 651, Hannah, Courtly Poets. Compare:
My mind to me a kingdom is;
Such perfect joy therein I find,
As far exceeds all earthly bliss
That God and Nature hath assigned.
Though much I want that most
would have,
Yet still my mind forbids to crave.
Byrd: Psalmes, Sonnets, etc. 1588.
My mind to me an empire is,
While grace affordeth health.
Robert Southwell (1560–1595), Loo Home.
"Mens regnum bona possidet" (translated as "A good mind possesses a kingdom"), Seneca, Thyestes, ii. 380.

Attributed to Oxford by May, but also published as the work of Edward Dyer.
Poems, Attributed

To Leon Goldensohn, June 15, 1946, from "The Nuremberg Interviews" by Leon Goldensohn, Robert Gellately - History - 2004
As quoted by Brian Masters (2011), Killing for Company, Random House, p. 189, ISBN 1446428737
Poem The Loveliness of Love http://www.umiacs.umd.edu/~ridge/local/iinbid.html

Source: Regards sur le monde actuel [Reflections on the World Today] (1931), p. 172

As quoted in Making a Habit of Success: How to Make a Habit of Succeeding, How to Win With High Self-Esteem (1999) by MacK R. Douglas, p. 45. Unsourced variant: What this power is, I cannot say. All I know is that it exists... and it becomes available only when you are in that state of mind in which you know exactly what you want...and are fully determined not to quit until you get it.
Context: I had made up my mind to find that for which I was searching even if it required the remainder of my life. After innumerable failures I finally uncovered the principle for which I was searching, and I was astounded at its simplicity. I was still more astounded to discover the principle I had revealed not only beneficial in the construction of a mechanical hearing aid but it served as well as means of sending the sound of the voice over a wire. Another discovery which came out of my investigation was the fact that when a man gives his order to produce a definite result and stands by that order it seems to have the effect of giving him what might be termed a second sight which enables him to see right through ordinary problems. What this power is I cannot say; all I know is that it exists and it becomes available only when a man is in that state of mind in which he knows exactly what he wants and is fully determined not to quit until he finds it.

On working at an early age in order to communicate with her parents in “Jessica Alba's Reinvention” https://www.redbookmag.com/life/money-career/a19434170/jessicaalba/ in Redbook (2018 Mar 15)