It's rare that the deep thoughts of a world-class astronomer and thinker can be reduced to three and four-minute bite-sized chunks understandable to anyone and yet still rather profound -- but Sagan had a talent for reducing his outsized thoughts to something concentrated and digestible. Though his topics are huge in scope and wide-ranging in subject -- he'll pontificate on the nature of space, time, being -- his main objective seems to be getting the listener to shift their view on things a few degrees; to interrupt the routine way we tend to think about our existence and gain some new perspective. Here are a few of my favorite of his brain-bending conversation starters.

Animator and director Michael Cone created this video around a minute-long clip of Sagan talking about our view of the physical world, and how everything we take for granted about our existence in it are nothing more than rarely-questioned conventions.

Physical World from michael cone on Vimeo.

Pale Blue Dot is one of Sagan's most famous (and my favorite) pieces. The concept is nothing new -- the Earth is small; we are relatively insignificant -- but the way he talks about this is powerful indeed.

Sagan elaborates on his Pale Blue Dot thesis a bit in this short clip -- it's difficult to justify the divisions we sew among ourselves, he says, when our planet is viewed from space, just "a fragile blue crescent fadng to become an inconspicuous point of light against the vast citadel of the stars."

Sagan's famous explanation of the fourth dimension -- and his characterization of the perspective that all of us are trapped in, which he calls "Flatland" -- are absolutely classic and still totally fascinating.