The Readymade (n.) is not at all related to the 'found object' because the latter is completely directed by personal taste, which decides that this is a beautiful object and is unique.
The Readymade (n.) is a principle grounded in the idea of chosing an object that wouldn't attract, either by its beauty or by its ugliness. To find a point of indifference in looking at it, you see
The Readymade (n.) is a principle of assemblage at work in all art, for even the tubes of paint used by the artist are manufactured and ready made products.
The Readymade (n.) is an attempt to discourage aesthetics; and yet despite throwing the bottlerack and the urinal in the critic's faces, now they admire them for their aesthetic beauty.
The Readymade (n.) is likely the most important single idea to come out of Duchamp's work.