The meaning of this term, however, is not always the same. It may designate the act of instructing, the subject-matter or the doctrine imparted, a summary thereof, the text of the traditional chief parts, or a book containing the catechismal doctrine, text, or text with explanation. Luther used the word most frequently and preferably in the sense of instruction. This appears from the definitions quoted in the preceding paragraph, where catechism is defined as "sermon," "instruction," "Christian training," etc. "You have the catechism" (the doctrine), says Luther, "in small and large books." Bugenhagen defines thus: "Katechismus, dat is, christlike underrichtinge ut den teyn gebaden Gades." In the Apology, Melanchthon employs the word catechism as identical with _kathechesis puerorum,_ instruction of the young in the Christian fundamentals. (324, 41.) "Accordingly," says O. Albrecht, "catechism means elementary instruction in Christianity, conceived, first, as the act; then, as the material for instruction; then, as the contents of a book, and finally, as the book itself." This usage must be borne in mind also where Luther speaks of his own Catechisms. "German Catechism" means instruction in, or preaching on, the traditional chief parts in the German language. And while "Enchiridion" signifies a book of small compass, the title "Small Catechism" (as appears from the old subtitle: "Ein kleiner Katechismus oder christliche Zucht") means instruction in the chief parts, proceeding with compact brevity, and, at the same time, these parts themselves together with the explanations added. (W. 30, 1, 454. 539.) As the title of a book the word catechism was first employed by Althamer in 1528, and by Brenz as the subtitle of his "Questions" (_Fragestuecke_). A school-book written by John Colet in the beginning of the sixteenth century bears the title "_Catechyzon,_ The Instructor." (456.)