There is a significant difference between the idea of a bibliography as a complete record of books on a particular subject or of a particular kind and that of bibliographies of bibliographies as they have been ordinarily made. To some extent every bibliography serves a practical need, but bibliographies of bibliographies have at first served this need somewhat unconsciously and have served it more and more deliberately as time has passed. As my comments in this essay have shown, the bibliography of bibliographies has been characteristically a tool having immediate practical usefulness. There are few exceptions to this rule: Namur's careless book of 1838, Besterman's book that we have just examined, and Josephson's bibliography of bibliographies of bibliographies that we shall mention at the end of this chapter include works that the compilers regarded as having historical interest rather than practical value. Conrad Gesner named in 1548 a considerable number of classical Greek and Latin works because they seemed to his contemporaries to serve their needs. This aspect of immediate contemporary usefulness has remained characteristic of bibliographies of bibliographies down to the present time. References to classical authorities had still a certain degree of practical value for Labbé (1664) and Teissier (1686, 1705). They have disappeared completely or almost completely from later bibliographies of bibliographies. During the last century this emphasis on immediate contemporary usefulness has perhaps expressed itself more clearly in acts than in words. For example, Peignot in 1812 is already looking in this direction. Although subsequent bibliographers may include outmoded books, their eyes turn, as Petzholdt's did in 1866, more and more consciously to modern writings. The four most recent bibliographies of bibliographies recognize fully that they intend to be primarily guides to the best modern sources of information.