Labor Day has come and gone, and I am chagrined to find that I haven't made it through my summer reading. My list comprised only a single book, but a rather unusual one: the text is three billion years old, has six billion copies in print, runs three billion letters long (about one million pages), and is written entirely in four characters (A, T, C, G) with no spaces or punctuation. The book, of course, is a great classic, The Sequence of the Human Genome.

Just before the Fourth of July holiday, an international scientific consortium announced at a White House celebration that it had largely deciphered the DNA instructions encoded in the human chromosomes. I felt a special pride in the accomplishment, because my own scientific group at the Whitehead Institute Center for Genome Research was a major contributor to the effort.

Now that the hoopla has died down, we've all turned to the work of preparing a scientific paper to be submitted later this year describing the findings. The real challenge is ''annotating'' the sequence, attaching meaning to...