An assemblage of an artist's work, consisting of original prints, drawings, plates or reproductions which, unlike a printed book illustrated with plates, are not bound but form loose leaves in a portfolio (some may be in a passe-partout) or in a cloth-bound cassette or case. Portfolios are usually accompanied by an explanatory brochure and are usually published in limited editions. Portfolios are often devoted to an overarching theme or subject, as exemplified by the Max Pechstein portfolio of prints on the "Lord's Prayer" ["Vater unser"], in which the artist created a sequence of illustrations, each incorporating a section of the text of the Lord's Prayer.