It is one of those weird social things. Even as parents we say, oh, don't be sad. You know, come here, we'll distract you with some ice cream or something. And I don't know if that's always the best thing. But it's certainly - you understand why people do it.

The idea kind of started with me just thinking about what would be fun to see in animation, you know - what have I not seen? For some reason, I got thinking about the human body and realizing, well, I've seen, like, traveling through the bloodstream and into the, you know, stomach and things.

If you were feeling sad right now and you recall a sad - or, a very happy memory from the past, it will be tinged with more sadness based on your current feeling. So we felt like that was actually on solid scientific ground .

Every time you recall a memory, you're basically making another copy of it and at that same point it is susceptible to new changes and adaptations. So, you know, if you remember from when you were, you know, in second grade and there was Christmas and you got a present from your grandfather and your mom was wearing a red dress, that may or may not all have happened.

And as I was sort of doodling, I was thinking, surprise and fear - probably fairly similar so let's just lose surprise. And that left us with five.

So we can sit with Lee Unkrich and Andrew Stanton, and all the other folks and experience what the film is going to be like. And then we go away into a room, and we talk about what worked and what didn't. And then we take all of those findings and we do that whole process again.

You have to think about good storytelling and characters first. Then hopefully, the rest of that stuff will follow, some more than others. But if you don't have a good film and strong characters, then you don't have anything down the road.