[possibly from C. S. Lewis's "Narnia" books] An awesomely arcane technique central to a program or system, especially one neither generally published nor available to hackers at large (compare black art
); one that could only have been composed by a true wizard
Compiler optimisation techniques and many aspects of OS
design used to be deep magic
; many techniques in cryptography, signal processing, graphics, and AI still are.
Compare heavy wizardry
Especially found in comments of the form "Deep magic begins here.".
Compare voodoo programming