Thomas Merton (1915-1968) was one of the most influential spiritual writers of modern times. A Trappist monk, peace and civil rights activist, and widely-praised literary figure, he was also one of the most prolific and provocative letter writers of the twentieth century. His letters (those written both by him and to him), archived at the Thomas Merton Studies Center in Kentucky, number more than ten thousand. For Merton, letters were not just a vehicle for exchanging information, but his primary means for initiating, maintaining, and deepening relationships. Letter-writing was a personal act of self-revelation and communication. His letters offer a unique lens through which we relive the spiritual and social upheavals of the twentieth century, while offering wisdom that is still relevant for our world today.