Dear Sofia,
a dialogue between Sam and Max, taken from "Fair Wind to Java". Max: "We'll travel through this dimensional portal on top of the bar!" Sam: "That's spilled beer, Rockhead."
A dimensional portal is a wonderful way to escape from one story to another, like Lena in the "lilac flower" or like the dragon hunter, always changing to another world through a dimensional portal after defeating and killing a dragon.
I don't know who was the first who discovered that a story has not to be told in a linear way; the Odyssee of Homer is a stunning example, but even in the Gilgamesh-epic poem there is a story-within-a-story (the story of Utnapishtim). So even the oldest stories know the trick of the dimensional portal: to move through time and space.
Do you think there is another person in this world mentioning Gilgamesh rather than the internet as an example of non-linear story-telling?

Yours,
John