According to author Jon Wiener, "All You Need Is Love" served as "the anthem of flower power" during the summer of 1967 but also, like the Beatles' Sgt.
In 2009, George Vaillant, the chief investigator of the Grant Study, which tracked 268 Harvard undergraduates for a period of 80 years with the goal of finding what factors led to happiness, stated that its findings could be summarized as "Happiness is love.