The growing popularity of skeptical views created an intellectual crisis in seventeenth-century Europe. One major response was offered by the French philosopher and mathematician René Descartes (1596–1650). In his classic work, "Meditations of First Philosophy" (1641), Descartes sought to refute skepticism, but only after he had formulated the case for skepticism as powerfully as possible. Descartes argued that no matter what radical skeptical possibilities we imagine there are certain truths (e.g., that thinking is occurring, or that I exist) that are absolutely certain. Thus, the ancient skeptics were wrong to claim that knowledge is impossible. Descartes also attempted to refute skeptical doubts about the reliability of our senses, our memory, and other cognitive faculties. To do this, Descartes tried to prove that God exists and that God would not allow us to be systematically deceived about the nature of reality. Many contemporary philosophers question whether this second stage of Descartes' critique of skepticism is successful.