书马犬事，乃是《庄子》中的一则寓言故事。据说，有一位乡村老人，养了一匹马、一只狗和一头牛，三者相处和谐。有一天，老人发现他的马不见了，他的邻居都来安慰他，但老人却淡然处之，说：“这或许是福祸相依，谁知道呢？”没过多久，那匹马竟然自己回来了，而且还带来了一匹野马。邻居们听到这个消息后都赞叹不已，但老人仍然保持淡然，说：“这或许是祸福无常，谁知道呢？”接下来，老人的儿子骑上了新来的野马，但不幸的是，他从马上摔下来，摔断了腿。这一次，邻居们又来安慰老人，但老人仍然淡然，说：“这或许是祸福相依，谁知道呢？”不久后，一场战争爆发了，所有年轻人都被征召入伍，但老人的儿子因为他的伤势而被免除了征召，他幸免于难。

这则寓言故事通过老人的态度告诉我们，我们不能以一时的成败来判断事情的好坏，要保持一种淡然处之的心态，相信一切都会有好的结果。

The Story of the Book, Horse and Dog is a fable in the book Zhuangzi. It tells the story of an old farmer who had a horse, a dog and a cow, and they all lived harmoniously. One day, the farmer discovered that his horse was missing, and his neighbors came to console him, but the old man remained indifferent, saying, "Maybe it is a blessing in disguise, who knows?" Not long after, the horse came back by itself, and it even brought a wild horse with it. When the neighbors heard the news, they all praised the old man, but he remained indifferent, saying, "Maybe it is a change of fortune, who knows?" Next, the old man's son rode the new wild horse, but unfortunately, he fell off the horse and broke his leg. This time, the neighbors came to console the old man again, but he remained indifferent, saying, "Maybe it is a blessing in disguise, who knows?" Soon after, a war broke out, and all the young men were conscripted into the army, but the old man's son was exempt from military service because of his injury, and he was spared.

This fable tells us through the old man's attitude that we should not judge the good or bad of things by their success or failure at a moment in time. We should maintain a calm state of mind and believe that everything will have a good result.