On Being and Essence
This short treatise distinguishes what a thing is from its act of existing and examines genus, species and individuals in material and immaterial substances.
Understanding the text
Written early in Aquinas’s Paris career, it draws on Aristotle and Avicenna through the scholastic vocabulary of the thirteenth century.
Key points
- 01
Essence
Essence answers what a thing is without simply being identical with its actual existence.
- 02
Composition
Material substances are understood through form and matter; separate intelligences present a different problem.
- 03
Existence
The dependence of created being opens an argument about necessary being without making each distinction self-evident.
Explore the ideas in depth
Distinguish essence and existence
This short treatise distinguishes what a thing is from its act of existing and examines genus, species and individuals in material and immaterial substances.
Essence
Essence answers what a thing is without simply being identical with its actual existence. Written early in Aquinas’s Paris career, it draws on Aristotle and Avicenna through the scholastic vocabulary of the thirteenth century.
Composition
Material substances are understood through form and matter; separate intelligences present a different problem. Compare the examples of bodily and separate substances, then mark where Thomas introduces his sources.
Existence
The dependence of created being opens an argument about necessary being without making each distinction self-evident. This short treatise distinguishes what a thing is from its act of existing and examines genus, species and individuals in material and immaterial substances.
Questions to carry into your reading
- Can we understand what a thing would be without knowing whether it exists?
- Which examples support or complicate the distinction?
Compare the examples of bodily and separate substances, then mark where Thomas introduces his sources.
How to read it
Compare the examples of bodily and separate substances, then mark where Thomas introduces his sources.
Editions & sources
Summaries and key points are original editorial interpretations. They accompany reading the work and do not replace an edition of the text. Editorial method ↗