The tools and materials of Chinese calligraphy are basically composed of writing brush, ink, paper and inkstone, which are commonly referred to as the "Four Treasures of the Study". It roughly means that they are the four essential treasures in a scholar's study. In the Song Dynasty, Mei Yaochen wrote in his poem "On September 6th, I Boarded the Boat Again and Replied to Pan Xu Zhou's Paper and Inkstone": "The Four Treasures of the Study come from two regions; since then, you and I have appreciated and played with them." Lu You also mentioned in his poem "Living in Seclusion Without Guests, I Spend My Days With Nothing But Writing Brush, Ink, Paper And Inkstone For Company, So I Wrote A Long Poem For Fun": "Rarely do guests visit through the mountains and waters, only the four scholars of the study can be relied upon." Here, the "four scholars of the study" refers to the "Four Treasures of the Study" as well.