Its a secret. It's tempting to share but when you do share it, it's not yours alone anymore and the secret no longer is a secret.
DEFINITION of SECRET (from Merriam-Webster):
- kept from knowledge or view (hidden)
- marked by the habit of discretion (closemouthed)
- working with hidden aims or methods (undercover)
- not acknowledged
- remote from human frequentation or notice (secluded)
- revealed only to the initiated (esoteric)
- designed to elude observation or detection
- containing information whose unauthorized disclosure could endanger national security (confidential, top secret)
ORIGIN of SECRET: 1350–1400; Middle English secrette Old French secret Latin sēcrētus hidden, orig. past participle of sēcernere
Speaking of secret, Hugh Grant 'is now a father of three after having a secret son with a Swedish TV boss.' Read more at the Daily Mail.