The Divisions and Methods of the Sciences

Questions V and VI of St. Thomas Aquinas' Commentary on the De Trinitate of Boethius contain St. Thomas' most comprehensive treatment of the classification of the theoretical sciences and description of their methods. They examine the meaning of knowledge and science, the distinction between practical and theoretical science, and the modes of procedure of the three main theoretical sciences: physics, mathematics, and metaphysics. They also clarify the nature of an "intermediate science" (scientia media) partaking of both physics and mathematics. 

The Questions are preceded by the text of Boethius' De Trinitate which is the occasion of St. Thomas' raising his Questions concerning science, and his literal commentary on the text. A comparison of the literal commentary with the questions that follow shows on the one hand St. Thomas' dependence on the classical Boethian philosophy, and on the other his original development of that philosophy through his reading of philosophers like Aristotle and Avicenna and through his own personal insights. 

Three appendices translate the division of the sciences in St. Thomas' Commentary of Aristotle's Nichomachean Ethics, the nature of metaphysics in his Commentary on Aristotle's Metaphysics, and the order of learning the sciences proposed in several of his works.