Etymology
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silver bullet (n.)
"very effective, almost magical remedy," 1808. The belief in the magical power of silver weapons to conquer foes goes back at least to ancient Greece (as in Delphic Oracle's advice to Philip of Macedon).
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Brother Jonathan (n.)
sobriquet for "United States," 1816, often connected with Jonathan Trumbull (1740-1809) of Connecticut, who was called Brother Jonathan by George Washington, who often sought his advice, somehow in reference to 2 Sam i:26.
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brain trust (n.)
"group of experts assembled to give advice on some matter," occasionally used since early 1900s, it became current in 1933, in reference to the intellectuals gathered by U.S. President Franklin D. Roosevelt as advisers; from brain (n.) + trust (n.).
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back seat (n.)

also back-seat, 1832, originally of coaches, from back (adj.) + seat (n.). Used figuratively for "less or least prominent position" by 1868. Back-seat driver attested by 1923.

You know him. The one who sits on the back seat and tells the driver what to do. He issues a lot of instructions, gives advice, offers no end of criticism and doesn't do a bit of work. ["The Back Seat Driver," Wisconsin Congregational Church Life, May 1923]
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