The five-character formula of "falling", "taking the lead", "hook", "case" and "arriving" in writing is also called drawing pen. Pen is the basic method of calligraphy. In a broad sense, using a brush refers to the method of writing calligraphy works with a brush, including the method of holding a brush and the method of lifting a brush. In a narrow sense, brushwork refers to the method of sending pens when writing points, paintings and characters in books.