Is It Better to Iterate a Higher Level of Abstraction?

In less than 18 you state it's cheaper to iterate ta higher level of abstraction. Can you take us through abstraction, prototyping, modelling, designs, things like that? Sure. So we start progressively moving from concept to something that's more tangible. And at the lowest level of abstraction, when you're building a piece of software, you have code. That's the ultimate reality, of course. But all those things expand as you're going down that abstraction scale.