[2] Gall's main research interest was the behavioral and developmental problems of children, on which subject he published several scientific papers and books.
As a sideline he conducted more general research on the question of what makes systems work and fail.
[5] He collected and analyzed all kinds of examples of systems-failures, and generalized problems and pitfalls into a series of "Laws of Systems".
[6] In 2002 Gall also published a historical novel on Hatshepsut, queen of ancient Egypt in the Eighteenth Dynasty.
The work cites Murphy's Law and the Peter Principle, and includes similar sayings.
[full citation needed] This philosophy can also be attributed to extreme programming, which encourages doing the simplest thing first and adding features later.
[10] Notable were the quotations of Gall's Law by Grady Booch since 1991,[11] which were mentioned in multiple sources.