This is a paragraph from Kent Beck's book on Test Driven Development:
Clean code that works – now. This is the seeming contradiction that lies behind much of the pain of programming. Test-driven development replies to this contradiction with a paradox – test the program before you write it.
What is the seeming contradiction in the first line of the above paragraph? If I take the meaning of seeming as apparent, I don't see the connection between seeming and contradiction in the above paragraph. What is it that is apparently contradictory in that line?