La Multiplicidad de los Entes según Tomás de Aquino

These PhD Dissertation published as a book is a research on Metaphysics about the problem of Multiplicity explained by its principles on the grounds of Aristotle's Metaphysics focused on substance and metaphysical thought of Aquinas. According to Aquinas the multitude of forms are the cause of multiplicity of beings. Super Boethium De Trinitate has an importan treatment of matter and form as causes of substantial identity, of substance's non-being and something else and be a this. Therefore the multiplicity of beings is not explained only by virtue of the diversity of matter or by virtue of the susceptive subject. The main cause is the division of forms.