When the Swedish Academy bestows the Nobel Prize on a Scandinavian poet, it is hard not to be skeptical. After all, the academy has managed to award the prize to three Swedish poets alone, and the last such poet — Harry Martinson in 1974 — was actually a member of the academy at the time. But it would be wrong to scold the Swedes for elevating their countryman Tomas Transtromer. Mr. Transtromer is not only a first-rate artist, but his selection, announced Thursday, corrects an almost 15-year drought for poetry.