Fred Brooks

The fundamental problem with program maintenance is that fixing a defect has a substantial chance of introducing another.

The programmer, like the poet, works only slightly removed from pure thought-stuff. He builds his castles in the air, from air, creating by exertion of the imagination. Few media of creation are so flexible, so easy to polish and rework, so readily capable of realizing grand conceptual structures.

Adding manpower to a late software project makes it later