For some years now, I have realized how many false opinions I had accepted as true since my childhood. I became aware that at some stage in my life, the entire structure had to be completely dismantled. In Descartes' Meditations, one of the foundational texts of Western philosophy, the thinker rejects all of his previous beliefs in search of new certainties. He discovers his existence as a thinking being through the very exercise of doubt, progressing to the proof of God's existence, who guarantees his clear and distinct ideas as a means of access to truth. He raises new conceptual approaches to the body and mind, capable of serving as foundations for the new science of nature. Later philosophy has addressed Descartes' legacy, questioning many of his conclusions and even his fundamental approach, but his arguments have set the agenda for many of the greatest philosophical thinkers, and their allure remains. This new translation fully includes the Third and Fourth Replies and a selection of the other exchanges with Descartes' contemporaries that helped develop his philosophy.