Genius, like humanity, rusts for want of use. William Hazlitt
Iron rusts from disuse; water loses its purity from stagnation... even so does inaction sap the vigor of the mind. Leonardo da Vinci
I never drink water; that is the stuff that rusts pipes. W. C. Fields
The tongue of woman is her sword, which never rusts. Japanese Proverb
Iron that is not used soon rusts. Portuguese Proverb
Old love never rusts. Swedish Proverb