"৳ For example; if a person sits, the opinion formed of him that he is seated, is of necessity true: but by inverting the phrase, if the opinion is true that he is seated, he must necessarily sit. In both cases then there is a necessity; in the latter, that the person sits; in the former, that the opinion concerning him is true: but the person doth not sit, because the opinion of his sitting is true; but the opinion is rather true, because the action of his being seated was antecedent in time. Thus tho' the truth of the opinion may be the effect of the person taking a seat, there is nevertheless a necessity common to both."