Old minds are like old horses; you must exercise them if you wish to keep them in working order.

Liberty is the right of doing whatever laws permit.

聪明人说话，是因为有些话要说；蠢人说话，则因为要说些话。

生活教会我，即使在最黑暗的时刻，也总有一线光明。

The only limits in life are the ones you make.

"We are all in the gutter, but some of us are looking at the stars."

Every mental state is a function of some physical state of the brain.