The price of freedom is eternal vigilance.

Quality should never be compromised, not even for the sake of speed.

A proof is a device for convincing someone else that a mathematical statement is true.

出自汉·桓宽《盐铁论·相刺》。释义：碎玉满箱，算不得拥有财宝；读了几箱子的书，也不等于就掌握了其中的道理。