On the difficulty of programming...

The challenges of software were more subtle. In 1947 and 1948
von Neumann and Goldstine produced a series of reports called

  'Planning and Coding Problems 
   for an Electronic Computing Instrument'.

In these reports they set down dozens of routines for mathematical
computation with the expectation that some lowly "coder" would be able
to convert them into working programs.

It was not to be. The process of writing programs and getting
them to work was excruciatingly difficult. The first to make this
discovery was Maurice Wilkes, the University of Cambridge
computer scientist who had created EDSAC, the first practical
stored-program computer. In his Memoirs, Wilkes ruefully recalled
the moment in 1949 when 

   "the realization came over me with full force that 
    a good part of the remainder of my life was going to
    be spent in finding errors in my own programs."

                from: Scientific American, September 2009

                Obviously this was before OOP :)