An appellate court may interfere with a trial court's findings of credibility where the reasons given for accepting certain evidence are unsatisfactory and the probabilities do not support those findings. In determining what was agreed to be sold under a contract of sale, contemporaneous documentary evidence (including correspondence between the parties, notes made at the time of agreement, mortgage bond documentation, and formal notices of withdrawal) carries significant weight and may outweigh later oral testimony, particularly where such documentary evidence is corroborated by multiple independent sources. The probabilities are crucial in assessing credibility, and where overwhelming probabilities support one version of events through corroborated documentary and oral evidence, a trial court's contrary finding may be set aside on appeal.