Late night thoughts have a foreboding, and thus it is with Thomas: in his third compilation of magazine and newspaper pieces, he saves the title essay for last. It is a foreboding about the bomb and the foolishness of governments. "I am old enough by this time to be used to the notion of dying," he says. Now, hearing the cellos at the end of the Mahler pick up fragments from the first movement, "as though prepared to begin everything all over again," he remarks that he used to hear this as a wonderful few seconds of encouragement. Instead, with a pamphlet on MX-basing in front of him, the cellos "sound in my mind like the opening of all the hatches and the instant before ignition." Several of these essays--including the first, "The Unforgettable Fire"--are eloquent dark statements by a somber Thomas who sees little hope except perhaps from enough people reading the documents and writings on Hiroshima and Nagasaki. In other essays, of a more familiar sort, Thomas eyes nature with his special vision. A favorite, "On Smell," will appeal to all who have savored autumn leaf bonfires, now succeeded by "great black plastic bags, set out at the curb like wrapped corpses." The range of delights may be gleaned from the titles: "On Alchemy"--about the emergence of the "soft," or behavioral sciences; "Altruism"--some amusing turns on sociobiology. Other pieces of a scientific sort include one on dementia; a personal chronicle of the installation of a pacemaker; and, inevitably, one on language. And there is Thomas' list of the new seven wonders of the world (solicited by the New York Times)--where he has again found a miraculous symbiosis between two distinct species, as well as some very grand wonders indeed. Any Thomas is worth reading. These essays, with their theme and coda on nuclear holocaust, add a note of gravity that is new.