If we compare storytelling and the way we acquire languages to a blade of grass, we can say that the root system is the input and the blade of grass itself is the output.
The input must precede the output and act as the foundation and base for any output that follows.
The blade (speech and writing) exists because of the roots. The roots (listening and reading) don’t depend on the blade except to be beautiful and absorb sunlight and bring those sun nutrients down into them.
The water is the comprehensible input.