That is indeed the general idea. That's why they're called "concepts", they're meant to be things, or categories of things, that we perceive. But "concept" also has a technical sense, of the assumed representation in machine learning.
That is, in machine learning a concept is represented as a set of instances. Inside the human mind, who knows.
That is, in machine learning a concept is represented as a set of instances. Inside the human mind, who knows.