use one's brain

But trying to use one's brains is bad business!

The clarity of mind and the understanding-the ability to use one's brain down to the ultimate cell.

To prosper there, "one must use one's brains for a living", and as "brains are mobile, you can't tax them too much."

"The intellectual life is a good one, to use one's brain, to uncover the secrets of reality, that is a gift granted to very few.

Offhand," he added amiably, "it would seem that using one's brains would be classed as a political offense rather than a criminal one on Walden.

In the main part of the book he asks whether reflective intelligence - never clearly defined, but apparently the capacity to use one's brain consciously and systematically, to make the most of one's g - can be increased, and if so, how.