Full Idea
We do not say that he is a good man when, having his hands tied up, he is hindered from doing the mischief he designs; …hence it is by affection merely that a creature is esteemed good or ill, natural or unnatural.
Clarification
'Affections' are any desires or emotions
Gist of Idea
A person isn't good if only tying their hands prevents their mischief, so the affections decide a person's morality
Source
3rd Earl of Shaftesbury (Inquiry Concerning Virtue or Merit [1699], I.II.I)
Book Reference
'British Moralists 1650-1800 Vol. 1', ed/tr. Raphael,D.D. [Hackett 1991], p.172
A Reaction
Note that he more or less equates being morally 'ill' with being 'unnatural'. We tend to reserve 'unnatural' for extreme or perverse crimes. Personally I would place more emphasis on evil judgements, and less on evil feelings.