There is no other cause of all depression and despair than the inability of seeing through life. There may be many reasons apparently seeming to be the different causes of unhappiness, but this one is the greatest reason, the reason of all reasons. Even animals in whose nature the tendency of fighting is pronounced become friends when they come to know one another by association. Many troubles in the life of individuals and of the multitude might be avoided if keen insight were developed, for all confusion is caused by misunderstanding. Not only human beings, but all things of this world which seem of use or of no use, which seem to be easy or difficult to obtain, all are for the use of man. Therefore penetration into things is the secret of the success of science, art, philosophy and religion, all.