Five, one to write a review of all the existing light bulbs so you can decide which one to buy, another one to write a remarkably similar one in another magazine the next month, a third to have a big one come out on glossy paper two months later that is by then completely out of date, a fourth to hint in his or her column that a completely new and updated bulb is coming out, and the fifth to report a rumor that that new bulb is shipping with a virus.