Theory
Theory (n.) An analysis that can never be entirely right, but can be entirely wrong.
In theory, theory is, of course perfect, but in practice, practice is better. The first mathematician programmers, who made a program by winding wire around the pins of a circuit board, were astonished when they discovered they had made mistakes. They literally had not understood that their theories and equations could contain bugs and it pained them to have to depend on a machine to correct them.