Where is an idea created from?

We who are called an art director and a designer think about a new idea as every day, and there must be it. Advertisement development to be, for example, new. Layout and a color of the poster which seems to stand out at a street corner. There is many that it is demanded visual covers of a magazine new idea. Where will such an idea be created from?
If there is nothing, a flash is created from the time and does not come. I see a fruit of an apple falling from a tree, and an episode of physicist Newton who discovered universal gravitation is famous. However, it did not flash simply, and an apple triggers it off, and it is always for a new way of thinking to have been made to have by Newton who thought about a thing of gravitation. The event that seemed to be natural that an apple fell hanged down a flash to Newton in thought. I wear one implication that I change an angle and try to think about a thing and was different. And a combination of a new element is finished.
An unexpected combination of one thought becomes the basics of a new idea in a brain already. If I think in reality more and will bring up the basics, I am good. It is a many-sided way of thinking that is the most important.