The most terrible enemy is the lack of strong faith-romain rolland. Nothing is difficult in the world, as long as you are willing to climb-Mao Zedong. In fact, there is no road in the world, and more people will become roads-Lu Xun. Suffering is the highest institution of learning to temper personality-Liang Qichao. There is no royal road to science, and only those who do not dread the fatiguing climb along steep mountain roads can hope to reach the glorious summit-Marx. God put many obstacles in the way just to strengthen your will-Tagore.