settled back in his chair and began whispering again to the Blue Doctor
next to him.

A Green Doctor cleared his throat. "Doctor Timgar, what do you consider
to be the basic principle that underlies the work and services of
physicians of Hospital Earth?"

It was an old question, a favorite on freshman medical school
examinations. "The principle that environments and life forms in the
universe may be dissimilar, but that biochemical reactions are universal
throughout creation," Dal said slowly.

"Well memorized," Black Doctor Tanner said sourly. "What does it mean?"

"It means that the principles of chemistry, physiology, pathology and
the other life sciences, once understood, can be applied to any living
creature in the universe, and will be found valid," Dal said. "As
different as the various life forms may be, the basic life processes in
one life form are the same, under different conditions, as the life
processes in any other life form, just as hydrogen and oxygen will
combine to form water anywhere in the universe where the proper physical
conditions prevail."

"Very good, very good," the Green Doctor said. "But tell me this: what
in your opinion is the place of surgery in a Galactic practice of
medicine?"

A more difficult question, but one that Dal's training had prepared him
well to answer. He answered it, and faced another question, and another.
One by one, the doctors interrogated him, Black Doctor Arnquist among