Complexity.
Nothing quite embodies the word like the human brain.
So for centuries we've studied the complexity of the human brain using the tools and technology of the day.
If that's pen and paper from the age of da Vinci through advents in microscopy to be able to look more deeply into the brain to a lot of the new technologies that you've heard about today through imaging, magnetic resonance imaging, able to look a the details of the brain.