The story of fish and bear's paw originated from Mencius written by Mencius in BC. Philosophers use fish and bear's paw as metaphors in their articles, explaining that two things you love cannot be obtained at the same time. After comparing, be sure to choose the one you love more. Today, excellent service and low price are like "fish" and "bear's paw" written by Meng Xianzhe, but modern people are not better than the ancients. Cheap and excellent "* * * knowledge" has already cultivated their mentality of having both fish and bear's paw. However, the market is a market after all, and its internal laws cannot be changed. So, will the old adage that you can't have your cake and eat it?