On one occasion, sima guang with friends to play in the backyard. The yard has a large water tanks, have a baby climb to the cylinder on the play, accidentally, fell into the tank factory. Large cylinder depth, saw the child was heavily silted. The accident happened to the other children saw, scared to cry while shouted, ran to the outside to adults for help. Sima guang has used his quick wits, picked up a big stone from the ground, his strength to the tank go, "bang!" Out of the tank is broken, the water flow in the cylinder, submerged in the water of the child is saved. Small sima guang, a calm demeanor, since the childhood is a pair of grownup look like. This is a story circulates "sima guang hit a cylinder".
有一次，司马光跟小伙伴们在后院里玩耍。院子里有一口大水缸，有个小孩爬到缸沿上玩，一不小心，掉到缸厂里。缸大水深，眼看那孩子快要没顶了。别的孩子们一见出了事，吓得边哭边喊，跑到外面向大人求救。司马光却急中生智，从地上捡起一块大石头，使劲向水缸砸去，"砰!"水缸破了，缸里的水流了出来，被淹在水里的小孩也得救了。小小的司马光遇事沉着冷静，从小就是一副小大人模样。这就是流传至今"司马光砸缸"的故事。
