All human knowledge is from experience.
天下的事情，祸患常常产生于疏忽细微之处，而人的志向也要警惕逐渐放纵。
一门科学的历史就是它的问题域的历史。
States are rational actors that seek to maximize their power and security in an anarchic international system.
"Sometimes the hardest thing to do is to tell the simplest truth."
