Britain, wellspring of the industrial revolution, is the chief proof of this theory.

ECONOMIST: Creating economic wealth

However, all the researchers involved are keen to stress that their finding falls a long way short of proof for this theory.

BBC: Clues to massive leukaemia rise

The charitable ways of Gates and Buffett also provide living proof that the "trickle-down theory" is in fact reality.

FORBES: Magazine Article

Theory is great, but the proof is in the pudding.

FORBES: Malkiel Shills For Indexing Again, But Backs Baidu Just In Case

When a theory emerges consistent with the facts, the proof is with science, the truth is with science.

NPR: Serenading Science In A New Rock Album

In theory, a wide range of improved materials could be made in nanocrystalline form: more proof that small is beautiful.

ECONOMIST: Nanotechnology