Full Idea
In 'Metaphysics' Aristotle argues that the various senses of being must be understood with reference to being in one primary sense, the being of substance.
Gist of Idea
Being must be understood with reference to one primary sense - the being of substance
Source
report of Aristotle (Metaphysics [c.324 BCE], 1 Intro) by Mary Louise Gill - Aristotle on Substance
Book Reference
Gill,Mary Louise: 'Aristotle on Substance: Paradox of Unity' [Princeton 1989], p.13
A Reaction
This I take (with limited knowledge of such things) to be the key message that needs to be grasped by the followers of Hegel and Heidegger, who seem to think you can grasp Being either directly, or through human experience of it.