It is therefore worthwhile, to search out the bounds between opinion and knowledge; and examine by what measures, in things, whereof we have no certain knowledge, we ought to regulate our assent, and moderate our persuasions.
John LockeChildren should from the beginning be bred up in an abhorrence of killing or tormenting any living creature; and be taught not to spoil or destroy any thing, unless it be for the preservation or advantage of some other that is nobler.
John Locke