Way back in 1899 (revised 1903), John Cotton Dana wrote in A Library Primer (now available online!):

“The librarian should have culture, scholarship, and executive ability. He should keep always in advance of his community, and constantly educate it to make greater demands upon him. He should be a leader and a teacher, earnest, enthusiastic, and intelligent. He should be able to win the confidence of children, and wise to lead them by easy steps from good books to the best. He has the greatest opportunity of any teacher in the community. He should be the teacher of teachers. He should make the library a school for the young, a college for adults, and the constant center of such educational activity as will make wholesome and inspiring themes the burden of the common thought. He should be enough of a bookworm to have a decided taste and fondness for books, and at the same time not enough to be such a recluse as loses sight of the point of view of those who know little of books.”