Quill knives were used until the end of the 19th Century to cut and shape the end of a large feather (the quill is the hollow shaft at the base of the feather) to form a writing pen. Most quill knives are single-bladed but they can have any number of blades. However, not all small knives are quill knives. A quill blade is usually much shorter than its handle and on the single-bladed ones the spring usually wraps around the head end and partially fills the blade cavity. Ironically, while most quill knives are jack knives, most “pen” knives are not quill knives.