run head against a brick wall
run (one's) head against a brick wall
To attempt, continually and fruitlessly, to accomplish some task or achieve some goal that is or seems ultimately hopeless. I feel like I've been running my head against a brick wall trying to understand this math equation. Some people are never going to agree with you on this, so it's no use running your head against a brick wall trying to convince everyone.
run one's head against a brick wall
Fig. to be frustrated by coming up against an insurmountable obstacle. There is no point in running your head against a brick wall. If you can't succeed in this case, don't even try. I have been running my head against a brick wall about this problem long enough.
run one's head against (into) a brick/stone wall, to
To make vain efforts against insurmountable difficulties. This expression, with its vivid image of futility, dates from the sixteenth century, when John Lyly (or some other author) wrote, “Thou shalt . . . have thy head runne against a stone wall” (1589). Other equally hard objects, like doors, were cited in similar fashion. By 1887, however, it was “If we run our heads against walls we’re safe to hurt ourselves” (M. Sergeant, Jacobi’s Wife, 1.1).