Motive may be inferred only when the stimuli in the agent's environment are open to view and the influences leading an agent to a particular action can be evaluated.

Boy, when you come to study something, and you come to understand it - you know, even if it's just a little discovery that you make, and you come to understand it on your own, it feels it's like the greatest high. It's like you just have found some incredibly secretive thing about nature.

Saturn is accompanied by a very large and diverse collection of moons. They range in size from a few kilometers across to as big across as the U.S.

The Saturn system is a rich planetary system. It offers mystery, scientific insight, and obviously splendour beyond compare, and the investigation of this system has enormous cosmic reach... just studying the rings alone, we stand to learn a lot about the discs of stars and gas that we call the spiral galaxies.

It's like there's a pulsating, hidden world, governed by ancient laws and principles, underlying everything around us - from the movements of electrical charges to the motions of the planets - and most people are completely unaware of it. To me, that's a shame.