A personality test aims to escribe aspects of a person's character that remain stable throughout that person's lifetime, the individual's character pattern of behavior, thoughts, and feelings. An early model of personality was posited by Greek philosopher/physician Hippocrates. The 20th century heralded a new interest in defining and identifying separate personality types, in close correlation with the emergence of the field of psychology. As such, several distinct tests emerged; some attempt to identify specific characteristics, while others attempt to identify personality as a whole.