The exact meaning of principle can depend upon its context. For example:
"our guiding principles" — basic moral beliefs that guide decisions and behavior
"electromagnetic principles" — rules describing how the world works
"She lacks principles." — lacks moral guidelines
"We agree in principle." — about important basic beliefs
At the time, I set it down to some idiosyncratic, personal distaste, and merely wondered at the acuteness of the symptoms; but I have since had reason to believe the cause to lie much deeper in the nature of man, and to turn on some nobler hinge than the principle of hatred.
There are no more uses of "principle" in Dr. Jekyll and Mr. Hyde.