胸有成竹

In the song Dynasty(960-1279), there was a scholar whose name was Wen Tong and who styled himself Yuke. He was not only admired by others for his great learning, but also enjoyed widespread renowned for his bamboo drawing. Every day there were always quite a few people who called at his house to ask for one of his bamboo drawings.
Actually, Wen Tong loved bamboos so much that he had grown various bamboos everywhere around his house. No matter what season it was and no matter whether it was sunny or rainy, he used to go to the bamboo forest to observe how they were growing. He pondered over the length and breadth of the bamboo poles as well as the shapes and colors of the leaves. Whenever he had gained a new understanding, he went back to his study, spread a piece of paper and prepared some ink by rubbing an ink stick on an ink slab, and drew what was in his mind on the paper. Through accumulation over a long period of time, the images of the bamboo in different seasons, under different weather conditions and at different moments were deeply imprinted in his mind. So whenever he stood before the paper and picked up a painting brush with concentrated attention,the various forms of the bamboo which he had observed at ordinary times at once rose before his eyes. And so every time he was drawing bamboos he appeared confident and at ease, and all the bamboos he had painted were very vivid and true to lift.
When people spoke highly of his paintings, he always said modestly that he had just put the images of the bamboo imprinted in his mind on the paper.
A young man wanted to learn bamboo drawing; when he knew that Chao Buzhi had made a profound study of Wen Tong's art of drawing, he went to Chao Buzhi for instruction. Chao Buzhi wrote a poem to him. In the poem, there are the following two lines:
When Yuke was painting the bamboos,
He had their images ready in his bosom.
Later people have summarized the lines as " having had the images of the bamboo ready in one's bosom," which means having had ready plans or designs in one's mind before doing a certain job so that its success is guaranteed. It is also used to mean being calm and cool - headed in dealingwith things.

北宋画家文同，字与可。他画的竹子远近闻名，每天总有不少人登门求画。文同画竹的妙诀在哪里呢？
原来，文同在自己家的房前屋后种上各种样的竹子，无论春夏秋冬，阴睛风雨，他经常去竹林观察竹子的生长变化情况，琢磨竹枝的长短粗细，叶子的形态、颜色，每当有新的感受就回到书房，铺纸研墨，把心中的印象画在纸上。目积月累，竹子在不同季节、不同天气、不同时辰的形象都深深地印在他的心中，只要凝神提笔，在画纸前一站，平日观察到的各种形态的竹子立刻浮现在眼前。所以每次画竹，他都显得非常从容自信，画出的竹子，无不逼真传神。
当人们夸奖他的画时，他总是谦虚地说：“我只是把心中琢磨成熟的竹子画下来罢了。”
有位青年想学画竹，得知诗人晁补之对文同的画很有研究，前往求教。晃补之写了一首诗送给他，其中有两句：“与可画竹，胸中有成竹。”
“胸有成竹”，比喻做事之前已作好充分准备，对事情的成功已有了十分的把握；又比喻遇事不慌，十分沉着。