First of all a natural talent is required; for when Nature opposes, everything else is in vain; but when Nature leads the way to what is most excellent, instruction in the art takes place.
It is most necessary to know the nature of the spine. One or more vertebrae may or may not go out of place very much and if they do, they are likely to produce serious complications and even death, if not properly adjusted. Many diseases are related to the spine.
Timidity betrays want of powers, and audacity a want of skill. There are, indeed, two things, knowledge and opinion, of which the one makes its possessor really to know, the other to be ignorant.
