To the Editor: A 1986 letter to the Editor (R15602CHDDJIFI) aptly suggested that in 1898 the polar explorer Dr. Frederick A. Cook conducted a natural "experiment"demonstrating the beneficial effects of light therapy for winter seasonal depression (R15602CHDBDDDJ). The letter quotes Cook-apparently alluding to the cosmos-writing that the result of Antarctic winter darkness was to leave people "in a condition similar to that of a planet deprived of direct sunlight."

In view of a novel theoretical model suggesting that human chronobiological sensitivity to light may share behavioral and molecular properties with the plant kingdom (R15602CHDCDDHC, R15602CHDDBBJE), it becomes reasonable to consider the possibility that the preceding Cook quotation represents a century-old typographical error and that Cook had intended to write that winter darkness left people in a condition similar to a plant deprived of direct sunlight. In support of this proposition, Cook's own writing elsewhere records that the depression induced by long polar nights implies "that the presence of the sun is essential to animal as it is to vegetable life" (R15602CHDCFJGJ).

At the least, Cook's long-forgotten insight makes one wonder what other clinically and biochemically relevant treasures from past scholarship might productively inform the future.