occurred in the textbooks of medieval logicians. Hubien (1975,1977) did the same in recent articles and other modern logicians with interest in the history of their field of knowledge, or students of the history of logic with knowledge of modern achievements in this field, could be mentioned. For example, Trentman (1977:41) in his recent edition of Vincent Ferrer's Tractatus de Suppositionibus, 'Treatise on suppositions', elucidates Ferrer's theory of natural supposition with the aid of modern logic and points out that in some respects, for example, in the theory of irltensionality, modern...