The Gay Science is considered the first fully composed work of Nietzsche's mature philosophy. It first articulated those themes that were later condensed into his 'doctrines,' including the death of God, amor fati, affirmation of life, the will to power, and perspectivism. Giorgio Colli already referred to it as "Nietzsche's most successful attempt at philosophical communication." Its reevaluation also marked the beginning of modern Nietzsche research.