庖丁解牛(포정해우)

포정이 소를 잡아 살과 뼈를 발라내다.
포정이라는 사람이 뛰어난 솜씨로 소의 살과 뼈를 발라내다.
포정이라는 백정이 문혜군을 위하여 소를 잡을 때에 뼈와 살이 다치지 않도록 긍경(肯綮)을 찾아 살을 잘 발라낸 고사에서 유래한다.
기술이나 솜씨가 신기에 가깝다.
기술이나 솜씨가 매우 뛰어나다.
遊刃有餘(유인유여)는 칼을 놀리는 솜씨가 여유롭다, 즉 솜씨 있게 일을 처리하다, 힘들이지 않고 여유 있게 일을 처리하다는 의미로 같은 표현이다.
do a task with skills and ease
be skilled at what one does
do something with ease
like a hot knife through butter
  
《莊子 養生主》 庖丁为文惠君解牛，手之所触，肩之所倚，足之所履，膝之所踦，砉然向然，奏刀騞然，莫不中音。合于《桑林》之舞，乃中《經首》之会。文惠君曰： "嘻，善哉！技蓋至此乎？" 庖丁释刀对曰： "臣之所好者道也，进乎技矣。始臣之解牛之时，所见无非牛者。三年之後，未嘗見全牛也。方今之时，臣以神遇而不以目视，官知止而神欲行。依乎天理，批大郤，导大窾，因其固然，技經肯綮之未嘗，而況大軱乎！ 良庖歲更刀，割也； 族庖月更刀，折也。今臣之刀十九年矣，所解數千牛矣，而刀刃若新发于硎。彼節者有間，而刀刃者無厚；以無厚入有間，恢恢乎其於游刃必有余地矣，是以十九年而刀刃若新發於硎。雖然，每至於族，吾見其難為，怵然為戒，視為止，行為遲。動刀甚微，謋然已解，如土委地。提刀而立，為之四顧，為之躊躇滿志，善刀而藏之。" 文惠君曰： "善哉！ 吾聞庖丁之言，得養生焉。"

《장자 양생주》 포정위문혜군해우，수지소촉，견지소의，족지소리，슬지소기，획연향연，주도획연，막부중음。합우《상림》지무，내중《경수》지회。문혜군왈： "희，선재！기개지차호？" 포정석도대왈： "신지소호자도야，진호기의。시신지해우지시，소견무비우자。삼년지후，미상견전우야。방금지시，신이신우이불이목시，관지지이신욕행。의호천리，비대극，도대관，인기고연，기경긍계지미상，이황대고호！ 양포세경도，할야；족포월경도，절야。금신지도십구년의，소해수천우의，이도인약신발우형。피절자유간，이도인자무후；이무후입유간，회회호기어유인필유여지의，시이십구년이도인약신발어형。수연，매지어족，오견기난위，출연위계，시위지，행위지。동도심미，획연이해，여토위지。제도이립，위지사고，위지주저만지，선도이장지。" 문혜군왈： "선재！ 오문포정지언，득양생언。"
His cook, Ding, cut up an ox for the ruler Wanhui. Whenever he applied his hand, leaned forward with his shoulder, planted his foot, and employed the pressure of his knee, in the audible ripping off of the skin, and slicing operation of the knife, the sounds were all in regular cadence. Movements and sounds proceeded as in the dance of the "Mulberry Forest" and the blended notes of Jingshou. The ruler said, "Ha, good! That your art should have become so perfect!" (Having finished his operation), the cook put down his knife, and replied, said, "What your servant loves is the method of the Dao, something in advance of any art. When I first began to cut up an ox, I saw nothing but the (entire) carcass. After three years I ceased to see it as a whole. Now I deal with it in a spirit-like manner, and do not look at it with my eyes. The use of my senses is discarded, and my spirit acts as it wills. Observing the natural lines, (my knife) slips through the great crevices and slides through the great cavities, taking advantage of the facilities thus presented. My art avoids the membranous ligatures, and much more the great bones!  A good cook changes his knife every year cutting; an ordinary cook changes his every month broken. Now my knife has been in use for nineteen years; it has cut up several thousand oxen, and yet its edge is as sharp as if it had newly come from the whetstone. There are the interstices of the joints, and the edge of the knife not thick; when that which is so thin enters where the interstice is, how easily it moves along! The blade has more than room enough. Nevertheless, whenever I come to a complicated joint, and see that there will be some difficulty, I proceed anxiously and with caution, not allowing my eyes to wander from the place, and moving my hand slowly. Then by a very slight movement of the knife, the part is quickly separated, and drops like earth to the ground. Then standing up with the knife in my hand, I look all round, and in a leisurely manner, self-satisfied, wipe it clean, and put it away." The ruler Wanhui said, "Good! I have heard the words of cook Ding, and learned from them to keep in good health."