How is petrarch an example of a humanism thinker and writer?

Francesco Petrarch is considered to be a Father of Humanism and Renaissance because he was one of the pillars of their doctrine. Humanism is epoch of the rebirth of a man as the center of the new world (but not without God). He was the one of the first poets, alongside Leonardo da Vinci and Giovanni Boccaccio, to speak and write about human internal conflicts, moral, ethics and love. His works that best represent his doctrine are "Secretum Meum" and "Canzioniere".