The Grand Canyon is proof of the power of this great river.

VOA: special.2009.08.12

Professor Yoshino explains. "Shakespeare calls this a problem of ocular proof, the idea that we need to see evidence before we believe in it -- and that,oftentimes, when metaphysical questions of guilt or innocence are difficult for us to answer, we have a tendency to reduce them to questions that pertain to physical evidence.

VOA: special.2011.06.06

He says Poland is now ready to be a responsible co-leader in Europe, and this signature is proof of that.

VOA: standard.2009.10.10

But if a farmer is given the opportunity to access and then makes a decision to buy, I think that's the real proof that this is something that's beneficial to them."

VOA: standard.2010.08.09