Tian Ji, a general of Qi, often raced horses against the princes for high stakes. Sun Bin noticed that the horses on each side were not far apart in speed and fell into three classes. He told Tian Ji: “Race your lowest team against their best, your best against their middle, and your middle against their lowest.”
Tian Ji lost one race and won two, and he took the king’s thousand pieces of gold. Afterwards he introduced Sun Bin to the king, who made him his teacher in war. (Records of the Grand Historian)