When a man is among friends he may get tired; sometimes he enjoys their society, but when he does not enjoy it, he thinks, "I am drained of all vitality." Why is this? It is the impression of their minds that has been produced in his mind. Perhaps someone has insulted him, or snubbed him, or told him this or that, and he goes among his friends bringing all his troubles with him; and then he leaves still saying, "I am tired." If he is working in a factory, it is reasonable to be tired in body; but why should he be tired in society where people are laughing and chatting? It is because their condition of mind is not like his.