Similar words: second sight, second string, second-hand store, second, secondly, second hand, secondhand, second-hand.
1. A friend is, as it were, a second self. 
2. A friend is a second self.
3. He is my best friend, my second self , as it were.
4. The gift is an irreversible transfer from ourselves to the second selves.
5. A friend is, as it were, a second self. - -- Cicero, Ancient Roman statesman.
6. A friend is, as it were, a second self. ---- Marcus Tullius Cicero.
More similar words: second sight, second string, second-hand store, second, secondly, second hand, secondhand, second-hand, secondary, nanosecond, second gear, secondment, second to none, split-second, second wind, picosecond, second best, split second, second mate, second-rate, second-guess, millisecond, second person, microsecond, secondarily, femtosecond, second coming, second-class, bits per second, second class.