The anonymous quote, "A daughter may outgrow your lap, but she will never outgrow your heart," is about loving one's daughter. This quote implies that no matter how old a daughter gets or how big she grows, she is still loved the same as when she was a little child. The bond between parents and their daughters is ageless.
The American journalist and author Jim Bishop specifically expresses the love a father has for his daughter in his quote about how he feels when his daughter dates: "Watching your daughter being collected by her date feels like handing over a million dollar Stradivarius to a gorilla." This quote suggests that no man is ever good enough to date his daughter, a feeling to which many loving fathers can relate.
Bishop compares his daughter to a Stradivarius, which is one of the stringed instruments that the members of the Stradivari family built during the 17th and 18th centuries. A Stradivarius is a highly valuable, irreplaceable treasure, like a daughter is in the eyes of a loving father. The idea that a date, who is a contender for his daughter's love, is a gorilla being handed a priceless instrument suggests that no man other than he can truly appreciate the worth of his daughter.