Aristotle's Ontology of Substances

Aquinas says we live in a universe of concrete individual substances that have natural, natural kinds forms but are also material. A particular individual is a substance just because it is a singular entity of a given kind. This panda bear, this kangaroo, this plant, this human being is a substance. We might think of this as a list of the building blocks of reality. What we find in substances that large in the world, you could think of it as the periodic table, not of chemicals, but of ontology.