This second volume of Hervaeus Natalis's polemical work, De quattuor materiis contains his De esse

et essentia. In this work the author criticizes the rival systems of the metaphysics of creation that

were upheld by Giles of Rome and Henry of Ghent, and presents an exposition of his own notion

of being. To explain Harvey's antagonistic attitude to Henry of Ghent and his simultaneous

rejection of Giles's positions (the rigid Aegidian real distinction between essence and existence

in particular) it was necessary to provide a thorough investigation of the ontological positions

of both Henry and Giles. Hence the lion's part of the Introduction is devoted to these two rivals of

Harvey's.

The selection of the manuscripts used for the present edition of De esse et essentia as well as the

ratio edendi, orthography, punctuation and headings employed, are explained in the General

Introduction to volume one, De formis (SA 30).