Thoreau and hay fever

Every spring, around the time the forsythia is in bloom, Jenn has a terrible time with nasal allergies. The English scientist Charles Blackley discovered in 1869 that pollen caused hay fever, but Thoreau was among those who suspected earlier that it might be the culprit. On June 21, 1860, he wrote, “Who knows but the pollen of some plants may be unwholesome to inhale, and produce the diseases of the season?”