As for the differences of opinion upon speculative questions, if we wait till they are reconciled, the action of human affairs must be suspended forever. But neither are we to look for perfection in any one man, nor for agreement among many.
Truth, then, seems to me, in the proper import of the word, to signify nothing but the joining or separating of Signs, as the Things signified by them do agree or disagree one with another. The joining or separating of signs here meant, is what by another name we call proposition. So that truth properly belongs only to propositions: whereof there are two sorts, viz. mental and verbal; as there are two sorts of signs commonly made use of, viz. ideas and words.
John Locke (1632 - 1704)
Source: Essay Concerning Human Understanding, 1690