" Let your mind become a lens, thanks to the converging rays of attention; let your soul be all intent on whatever it is that is established in your mind as a dominant, wholly absorbing idea.” This advice comes from Antonin-Dalmace Sertillanges, a Dominican friar and professor of moral philosophy, who during the early part of the twentieth century penned a slim but influential volume titled The Intellectual Life. Sertillanges wrote the book as a guide to “the development and deepening of the mind” for those called to make a living in the world of ideas. Throughout The Intellectual Life, Sertillanges recognizes the necessity of mastering complicated material and helps prepare the reader for this challenge. "

― Cal Newport , Deep Work: Rules for Focused Success in a Distracted World