After five years, Martin Arnold is packing in his “Making Books” column in the NYT. “I’ve had 212 opportunities to pronounce on what I still believe is the world’s primary cultural conduit. I have chronicled and commented on all sorts of literary trends, disputes, ups and downs, but the enduring consistence of what I have learned, the unrolling thread, has been about the durability and incandescence of books themselves; the bravery of those who write them; and the instinct to gamble by many, but not all, who publish them.”