Thinking is the hardest work there is, which is probably the reason why so few engage in it.
~ Henry Ford
Our opinions become fixed at the point where we stop thinking.
~ Ernest Renan
Clear thinking requires courage rather than intelligence.
~ Thomas Szasz
The mind ought sometimes to be diverted that it may return to better thinking.
Rarely do we find men who willingly engage in hard, solid thinking. There is an almost universal quest for easy answers and half-baked solutions. Nothing pains some people more than having to think.
~ Martin Luther King, Jr.
If I look confused it is because I am thinking.
~ Samuel Goldwyn
The best ideas come as jokes. Make your thinking as funny as possible.
~ David Ogilvy
Thinking: the talking of the soul with itself.