If you want to learn the history, go read "the history of PHP". There's tons opf it, none of it relevant to people who want to program modern PHP.

If you want to actually use PHP, or any other language, and the interpreter/compiler throws up errors that _cannot be understood_ by "using your brain" then that is both a bad design decision that should have been changed way back when, _and_ is a current bug in your interpreter/compiler that you need to fix.