The total mental efficiency of a man is the resultant of the working together of all his faculties. He is too complex a being for any one of them to have the casting vote. If any one of them do have the casting vote, it is more likely to be the strength of his desire and passion, the strength of the interest he takes in what is proposed. Concentration, memory, reasoning power, inventiveness, excellence of the senses, all are subsidiary to this.
William JamesWhen happiness is actually in possession, the thought of evil can no more acquire the feeling of reality than the thought of good can gain reality when melancholy rules. To the man actively happy, from whatever cause, evil simply cannot then and there be believed in.
William James