“Cleverness is not wisdom. And not to think mortal thoughts is to see few days.”

in a letter http://www.scribd.com/doc/5062627/Ryle to Professor Carlos Chagas, president of the Pontifical Academy of Sciences, 24 February 1983.
Context: The benefits of medical research are real - but so are the potential horrors of genetic engineering and embryo manipulation. We devise heart transplants, but do little for the 15 million who die annually of malnutrition and related diseases. Our cleverness has grown prodigiously - but not our wisdom.

Source: Small is Beautiful: A Study of Economics As If People Mattered (1973), p. 35.

The Now of Pooh.
Source: The Tao of Pooh (1982)
Context: Abstract cleverness of the mind only separates the thinker from the world of reality, and that world, the Forest of Real Life, is in a desperate condition now because of too many who think too much and care too little. In spite of what many minds have thought themselves into believing, that mistake cannot continue for much longer if everything is going to survive. The one chance we have to avoid certain disaster is to change our approach, and learn to value wisdom and contentment. These are things that are being searched for anyway, through Knowledge and Cleverness, but they do not come from Knowledge and Cleverness. They never have, and they never will. We can no longer afford to look so desperately hard for something in the wrong way and in the wrong place. If Knowledge and Cleverness are allowed to go on wrecking things, they will before much longer destroy all life on this earth as we know it, and what little may temporarily survive will not be worth looking at, even if it were possible for us to do so.

Maxim 441, trans. Stopp

Variant translation: All intelligent thoughts have already been thought; what is necessary is only to try to think them again.
Maxims and Reflections (1833)

Cheirones ("The Chirons")

Source: In the Woods

3 Minute Wonder, Episode 2
On Travel

Source: The Confessions of Aleister Crowley: An Autohagiography

It (1986)