truth will out

The phrase "truth will out", meaning "truth will become public", appears as early as William Shakespeare's works, in particular The Merchant of Venice. It may have been an entirely new concept of Shakespeare's, as he sees the need to explain its meaning as analogous to murder will out.

truth will out

1. A mystery will always be solved; truth will eventually and inevitably be discovered.

• phrases.org
• thefreedictionary