My impression was that it was the screwing around that was lacking.
“It was, of course, a grand and impressive thing to do, to mistrust the obvious, and to pin one’s faith in things which could not be seen!”
-Galen, a Roman doctor/philosopher, on Asclepiades's unwillingness to admit that the kidneys processed urine - despite Galen demonstrating the function of the kidneys to Asclepiades by, well, cutting open a live animal and pointing to the urine flowing from its kidneys to its bladder (search the page for "ligatures" to find Galen's experiment described), among other things.
Here's the new thread for posting quotes, with the usual rules: