Carry A Secret To The Grave

( not tell a secret during one's entire life ... )

A secret that you carry to the grave is something you never tell anyone during your entire lifetime. Example: "Please, you must not tell anyone what happened." Reply: "I will carry it to the grave."

Something you know but do not tell others is "a secret", and "a secret you carry to the grave" is a secret you do not tell anyone during your entire life. Example: "During his entire life, he never told anyone where he burried the money. He carried the secret to the grave."

When you don't tell even one person what happened, you "carry the secret to the grave". Example: "She and her sister were abused when they were children, but they never told anyone. They carried the secret to the grave."

If you do not tell anyone that secret during your entire life, you "carry it to the grave".