JUSTICE is a word in every man's mouth, but most commonly with a very undetermined, loose signification; which will always be so, unless a man has in his mind a distinct comprehension of the component parts that complex idea consists of and if it be decompounded, must be able to resolve it still only till he at last comes to the simple ideas that make it up
 John Locke, An Essay Concerning Human Understanding (1689). copy citation

Context

“This is very necessary in names of modes, and especially moral words; which, having no settled objects in nature, from whence their ideas are taken, as from their original, are apt to be very confused. JUSTICE is a word in every man's mouth, but most commonly with a very undetermined, loose signification; which will always be so, unless a man has in his mind a distinct comprehension of the component parts that complex idea consists of and if it be decompounded, must be able to resolve it still only till he at last comes to the simple ideas that make it up: and unless this be done, a man makes an ill use of the word, let it be justice, for example, or any other. I do not say, a man needs stand to recollect, and make this analysis at large, every time the word justice comes in his way:” source