It was a radical concept at the time, but has served our nation well.

As for the Wolves, let me advance a radical concept: it doesn't matter where they are or what's happened to them.

When Tennyson published his poem, women's higher education was a novel, even radical concept.

It was a radical concept, one that jarred his sensibilities.

This was a radical concept at the time.

But back then, world music was a radical concept.

Back in the early 70's this was still a radical concept.

I never would have presented so radical a concept with the sort of precarious hold I had on him.

It was a radical concept for its day, regardless of its limited scope.