together.

Cowpox had broken out on a farm near Berkeley and a dairy maid
called Sarah Neames contracted the disease. On May 14, 1796,
Dr. Jenner took some fluid from a sore on this woman's hand and
inoculated it by slight scratching into the arm of a healthy
boy eight years old, by name James Phipps. The boy had the
usual "reaction" or attack of vaccinia, a disorder
indistinguishable from the mildest form of smallpox. After an
interval of six weeks, on July 1, Jenner made the most
momentous but justifiable experiment, for he inoculated James
Phipps with smallpox by lymph taken from a sore on a case of
genuine, well-marked, human smallpox, AND THE BOY DID NOT TAKE
THE DISEASE AT ALL. Jenner waited till the nineteenth of the
month, and finding that the boy had still not developed
variola, he could hardly write for joy. "Listen," he wrote to
Gardner, "to the most delightful part of my story. The boy has
since been inoculated for the smallpox which, aS I VERNTURED TO
PREDICT, produced no effect. I shall now pursue my experiments
with redoubled ardor."

Here we are behind the scenes at a great discovery; "as I
ventured to predict"; prediction is part of scientific
theorizing; there is a place for legitimate prediction as there
is for experimentation. All discoverers have made predictions;
Harvey predicted the existence of the capillaries, Halley
predicted the return of his comet, Adams predicted the place of
the planet Neptune, the missing link in the evolutionary series
of the fossil horses had been predicted long before it was
actually found by Professor Marsh. Pasteur predicted that the