As far as I know, matrices were a “pure math” thing when they were first discovered and seemed pretty useless. Then physicists discovered them and used them for all sorts of shit and now they’re one of the most important tools in in science, engineering and programming.

Many good movies have been mentioned already (especially Eternal Sunshine of the spotless mind, Big Fish, Manchester by the sea and The Fountain).

I would like to add:

• Finding Neverland
• Captain Fantastic

And if you want to absolutely destroy yourself: Prayers for Bobby.