Taken from the 2004 WT library
[5-15-57 WT- 7 Those who really are growing in maturity find that familiarity with basic theocratic publications is a tremendous aid in their field ministry, enabling them to draw on a firm background of knowledge and thus to answer most of the questions they encounter in field service. Further, when they prepare a discourse for delivery at congregational meetings they do not merely rehash material that they presented in all their previous talks, but they search for further information that will make the talk really alive with sound spiritual counsel. Their zeal for knowledge may even prompt them to dig back into things that were published long before they came into the truth, expanding and deepening their understanding, and ever growing in Christian maturity.
8 Do you dig out older publications to expand and deepen your knowledge on subjects about which questions arise? Have you really studied these earlier publications? When a brother gives a talk, can you, to impress the information upon your mind further, identify the particular publication from which his points were taken? If he discusses Jesus’ earthly family, do you remember that the “Questions from Readers” section of the December 15, 1950, Watchtower told how we know that Jesus did have other brothers and sisters? When he points out that the Christian should not use profanity, do you remember that this was discussed in the article “Progress Toward Taming the Tongue,” February 15, 1951? When he tells about the different kinds of spirit creatures, namely, angels, cherubim, seraphim and the archangel, and describes their various positions, do you remember that this was considered on pages 50 to 53 of the book “The Truth Shall Make You Free”? Probably you will not remember the dates or page numbers, but do you remember the discussions? Can you use the Scripture index to find the pages? Can you explain these matters when someone questions you about them? Brothers who have a mature knowledge may even have recently looked up these subjects to refresh their memories on them before discussing them with newly interested persons.]