The idea of an instrumental opening to opera existed during the 17th century.

This idea of turning into a criminal from one day to the next doesn't exist.

As for other stars, none of her people had ever seen them and the idea did not exist.

And can an idea exist without being actually perceived?

The question in Oregon was whether new ideas could exist on a severe financial diet.

These things, or ideas, exist only in the mind that perceives them.

They then conclude that those ideas or perceived objects exist outside of the mind.

We see that the idea of the public interest on which a different view might perhaps be taken, actually hardly exists.

The idea that some places are "sacred" or especially holy has existed for many thousands of years.

These ideas did not exist in a vacuum; there was a political component as well.