Jonathan David Haidt is an American social psychologist and author.

Friedrich Wilhelm Nietzsche was a German philosopher and writer who started his career as a classical philologist and turned to philosophy early in his academic career.

Aldous Leonard Huxley was an English writer and philosopher.

Miguel Ángel Ruiz Macías, better known as Don Miguel Ruiz, is a Mexican author of Toltec spiritual and personal development texts..

Niccolò di Bernardo dei Machiavelli was a Florentine diplomat, author, philosopher, and historian who lived during the Italian Renaissance.

Lucius Annaeus Seneca the Elder, also known as Seneca the Rhetorician, was a Roman writer, born of a wealthy equestrian family of Corduba, Hispania.