best-laid plans go astray, the
Also, the best-laid schemes go astray. Even very careful designs or projects do not always succeed. For example, Mary spent all afternoon preparing this elaborate dish but forgot the most important ingredient—oh well, the best-laid plans go astray. This particular turn of phrase comes from Robert Burns's poem “To a Mouse” (1786): “The best-laid schemes o' mice an' men gang aft a-gley [go often astray].” It is so well known that it is often abbreviated to the best-laid plans.