Something could be true even if nobody knew that it were so. We therefore need a concept of truth that does not require of every truth that someone knows it. For this concept Bolzano introduced the term ‘Wahrheit an sich’ (‘truth in itself’). If something is a truth and no human being knows that it is, then — for Bolzano — it must be a “truth in itself”. A “truth in itself” (Wahrheit an sich) is nothing but a true proposition, i.e., a proposition that has the property of being true. Bolzano take