The beauty of instrumental variables is that they allow us to see the world in a new light.
Success in life means doing that which is the very best for us, under the conditions in which we are placed.
世俗的君子,如果他很穷你却说他很富,他就会发怒;如果他不义你却说他有义,就很高兴。 
The most important thing in life is to stop saying 'I wish' and start saying 'I will'.
The past is a kind of future that has already happened.