It's metaphysical. Like learning a foreign language widen your perspective. It's a particular insight you gain about the act of programming that makes you realize that you've been boxing yourself to a very small imperative/oop space.
Writing C code feels like writing a rule book, writing java feels like designing a lego set, writing lisp feels like writing proof, writing prolog feels like writing puzzles. Writing forth feels like writing a dictionary, then after that you write a few sentences. They're different feeling, but forth is one of the most flexible as you can go up and down from the most basic units to the high level ones. As another comment has mentioned, you can program forth where the basic units are elements from another language, and construct a dsl/dictionary out of it. Then switch the basic units while retaining your business logic for a faster implementation without a full rewrite.
Not just the realization you were boxed into a space, but also knowledge of stuff inside a different box. The more boxes you have the ability to access, the better.
Writing C code feels like writing a rule book, writing java feels like designing a lego set, writing lisp feels like writing proof, writing prolog feels like writing puzzles. Writing forth feels like writing a dictionary, then after that you write a few sentences. They're different feeling, but forth is one of the most flexible as you can go up and down from the most basic units to the high level ones. As another comment has mentioned, you can program forth where the basic units are elements from another language, and construct a dsl/dictionary out of it. Then switch the basic units while retaining your business logic for a faster implementation without a full rewrite.