pull oneself up by one's bootstraps

Early 19th century US; attested 1834. In original use, often used to refer to pulling oneself over a fence, and implying that someone is attempting or has claimed some ludicrously far-fetched or impossible task. Presumably a variant on a traditional tall tale, as elaborated below. The shift in sense to a possible task appears to have developed in the early 20th century, and the use of the phrase to mean “a ludicrous task” continued into the 1920s. Widely attributed since at least 1901 to The Surprising Adventures of Baron Munchausen, (1781) by Rudolf Erich Raspe, where the eponymous Baron pulls himself out of a swamp by his own pigtail, though not by his bootstraps. The Adventures is primarily a collection of centuries-old tall tales, however, and using bootstraps may have arisen as a variant on the same theme.