I’m late to the party, but I’ve just taken up the hobby whose popularity in the United States is second only to that of gardening and whose online presence is surpassed only by pornography. Stamp collecting, ham radio, amateur astronomy, knitting, and all the other traditional hobbies have their acolytes still; but they can scarcely compete with a hobby so excellently adapted to the Internet age, and so like the Internet itself with its recursive pathways and its population of ghosts and spirits.

The hobby, if you haven’t already guessed, is genealogy, and the opportunities for online participation in it are legion. Visit any of the leading sites—Ancestry.com or MyHeritage.com, for example—begin a free trial, plug in whatever names and dates come to mind, and in a matter of seconds you will receive scores, maybe hundreds, of demographic details culled (with the help of optical character recognition technology) from immigration, birth, death, and marriage records, from newspaper articles and shipping manifests, from city directories and census tables. Distant relatives who are at work on outer branches of your family tree may have made their findings publicly available, so that a mere touch of the mouse or trackpad can make them look like kissing cousins. Your great-great- uncle Harry may have his name enrolled on the database maintained by the Church of Jesus Christ of Latter-day Saints; happily, the Mormons will share with you everything they know about Uncle Harry for free, with no obligation to baptize him by proxy.

Add Uncle Harry to your family tree, and your genealogy program will reflect for just a moment and then reel off a series of suggestions. Was he, perhaps, the Harry Mishkin who took a cruise in the Bahamas in 1910? Or the Harry Mishkin whose wife Rachel emigrated from Russia via Liverpool in 1875? Though you think that he was born in 1870, might he still be alive?