The Ladon serpent protected the mythical tree of golden apples (venerated emblem of Venus). The golden apples of health and immortality were plundered once mortal Hercules killed Ladon during his 12th. labor.
This image brings to mind human relationships with the tree of knowledge and human nature. After Eve ate from the tree of knowledge, human paradise ended because what Eve did would let humans use knowledge to promote Evil. When an aspiring physician takes the Hippocratic Oath, he pledges to never use medical knowledge for do evil (including exploiting patients for self-gain).