The court shall consider no evidence which has not been formally offered. The purpose for which the evidence is offered must be specified. (Rule 132, Sec. 34, Rules of Court). The offer of evidence is necessary because it is the duty of the court to rest its findings of fact and its judgment only and strictly upon the evidence offered by the parties. Unless and until admitted by the court in evidence for the purpose or purposes for which such document is offered, the same is merely a scrap of paper barren of probative weight.