“The best sex takes place in the mind first”

Source: Spirit Bound

Variant: Problems cannot be solved with the same mind set that created them.

50
Ki Sayings (2003)
Context: The purpose of ki-aikido is not self-defence; that is a mere by product. It is far more important to learn to control the mind and body. It is too late to try to calm the mind after you take up the sword. First you must calm the mind and then take up the sword. When you raise the sword up overhead, do not cut your ki. Continue to calm the mind by half, half, half and create a living calmness in that infinite reduction. When practicing cutting with the sword, you will find infinitely more value in cutting just five to ten times with ki fully extended, than you would in cutting a thousand time with mere physical strength.

Source: Shantaram

"The Reach of Imagination" (1967)

Book IV, Ch. 19 : Of Enthusiasm (Chapter added in the fourth edition).
Variant paraphrase, sometimes cited as a direct quote: One unerring mark of the love of truth is not entertaining any proposition with greater assurance than the proofs it is built upon will warrant.
As paraphrased in Peter's Quotations : Ideas for our Time (1979) by Laurence J. Peter, p. 500; also in The Demon-Haunted World : Science as a Candle in the Dark (1994) by Carl Sagan, p. 64
An Essay Concerning Human Understanding (1689)
Context: He that would seriously set upon the search of truth, ought in the first place to prepare his mind with a love of it. For he that loves it not, will not take much pains to get it; nor be much concerned when he misses it. There is nobody in the commonwealth of learning who does not profess himself a lover of truth: and there is not a rational creature that would not take it amiss to be thought otherwise of. And yet, for all this, one may truly say, that there are very few lovers of truth, for truth's sake, even amongst those who persuade themselves that they are so. How a man may know whether he be so in earnest, is worth inquiry: and I think there is one unerring mark of it, viz. The not entertaining any proposition with greater assurance than the proofs it is built upon will warrant. Whoever goes beyond this measure of assent, it is plain receives not the truth in the love of it; loves not truth for truth's sake, but for some other bye-end.

The Architecture of Theories (1891)
Context: The origin of things, considered not as leading to anything, but in itself, contains the idea of First, the end of things that of Second, the process mediating between them that of Third. A philosophy which emphasises the idea of the One, is generally a dualistic philosophy in which the conception of Second receives exaggerated attention: for this One (though of course involving the idea of First) is always the other of a manifold which is not one. The idea of the Many, because variety is arbitrariness and arbitrariness is repudiation of any Secondness, has for its principal component the conception of First. In psychology Feeling is First, Sense of reaction Second, General conception Third, or mediation. In biology, the idea of arbitrary sporting is First, heredity is Second, the process whereby the accidental characters become fixed is Third. Chance is First, Law is Second, the tendency to take habits is Third. Mind is First, Matter is Second, Evolution is Third.