1900-1910: In 1900, Freud publishes The Interpretation of Dreams, which attempts to explain phenomena such as sexuality and abnormal desires.

Today: Freud remains popular, though many of his theories have been discredited.

1900-1910: The December 1900 issue of the Ladies' Home Journal predicts that exercise will become compulsory in schools and that by the year 2000 those who cannot walk ten miles a day will be considered weaklings.

Today: Obesity is a major health problem in both Western Europe and the Untied States, as people eat more and exercise less.

1900-1910: German philosopher Friedrich Nietzsche, who proclaimed "God is dead" and whose ideas influenced Hitler, dies.

Today: Nietzsche's ideas continue to influence philosophers and social theorists throughout the world.