In France human dissections were attended with such dangers that the young Vesalius transferred his field of labors to Italy, where such investigations were covertly permitted, if not openly countenanced.
From the very start the young Fleming looked askance at the accepted teachings of the day, and began a series of independent investigations based upon his own observations.

The results of these investigations he gave in a treatise on the subject which is regarded as the first comprehensive and systematic work on human anatomy.

This remarkable work was published in the author's twenty-eighth or twenty-ninth year.

Soon after this Vesalius was invited as imperial physician to the court of Emperor Charles V.He continued to act in the same capacity at the court of Philip II., after the abdication of his patron.

But in spite of this royal favor there was at work a factor more powerful than the influence of the monarch himself--an instrument that did so much to retard scientific progress, and by which so many lives were brought to a premature close.
Vesalius had received permission from the kinsmen of a certain grandee to perform an autopsy.