tell the truth from the bottom. Porcelain has a lot of key information. Foot is the only exposed part of porcelain, which can identify the tire soil. Through the rotary cutting trace of foot, we can judge the process, as well as manual blank and machine-made blank, and we can also see the clue from the circle foot. Distinguish between true and false from the bottom, and look at the year from the text. Porcelain inscriptions are memorable characters. For example, the "Fourteen Years of Chiwu" on the celadon tiger piece records the date of production, which belongs to the most calendar year in ceramics. "Yuan Yizuo, the Shangyu master of Huiji" is a pottery figure, which records the identity of a craftsman or workshop.