You can’t hold a cubic centimetre. Nor can you grasp an hour. You can’t touch money either—the physical thing you may be thinking of is cash, but it’s not money.
These are called abstractions. They are concepts that help us make sense of and operate in our world. We’re the only animal capable of developing, understanding, and thinking in abstractions. And although we can’t see or touch them, they’re extremely powerful tools that help us better organise society.
Perhaps the most interesting thing about these abstractions is they exist only because we all agree to believe in them.