The Last Supper - A Sketch of Leonardo's Art

Leonardo would try to look at facts and from them figure out the patterns and natural forces that cause these things to happen. In his notebook, he described his method, almost like a trick for closely observing a scene or an object. Look carefully and separately at each detail. He compared it to looking at the page of a book, which is meaningless when taken in as a whole but instead needs to be looked at word by word. The observation must be done in steps. If you wish to have a sound knowledge of the forms of objects, begin with the details of them and do not go on to the second step until you have first well fixed"