It is not the strongest of the species that survives, nor the most intelligent, but the one most responsive to change.  
The only meaningful way to study learning is through objective measurement.
The value of life lies not in the length of days,but in the use we make of them.
我从不担心行动的危险,我更担心不行动的危险。
It is a narrow mind which cannot look at a subject from various points of view.