When Carl Sagan studied the universe, he saw more than data and science. Known for popularizing and promoting public understanding of astronomy, the famed scientist was as much a creative thinker and writer as he was a planetary expert. He thought deeply about science and our solar system, seeing the forest for the trees, and the universe’s lessons among the “star stuff,” a term he made famous in an episode of his 13-part television show, Cosmos, which aired in the 1980s.

“We are a way for the universe to know itself. Some part of our being knows this is where we came from,” Sagan said on his show. “We long to return. And we can, because the cosmos is also within us. We’re made of star stuff.”

With profound lessons like this, Sagan applied a cosmic perspective to the human experience. He found awe in the interconnectedness of humans, Earth, and the solar system, and felt humbled learning that the same carbon, nitrogen, and oxygen atoms in our bodies were created by the stars some 4.5 billions years ago.

Sagan shared his scientific findings and life musings  on his popular TV show and in several influential books, including Cosmos (which accompanied the show), Pale Blue Dot: A Vision of the Human Future in Space, and Contact, which was made into a film (starring Jodie Foster) in 1997.

His primary goal? Make planetary science more accessible. A leader in the country’s early space endeavors, he undoubtedly succeeded — and inspired countless people along the way. Nearly 25 years after his passing, many still turn to Sagan for inspiration and grounding. Here are 15 of his lasting lessons on what the universe can teach us about life.

Imagination will often carry us to worlds that never were. But without it we go nowhere.
– "Cosmos," 1980

For small creatures such as we the vastness is bearable only through love.
– "Contact," 1985

Our preferences do not determine what’s true.
– "Skeptical Inquirer, 1995"

The Universe is not obliged to conform to what we consider comfortable or plausible.
– "Pale Blue Dot: A Vision of the Human Future in Space," 1994

Science is not only compatible with spirituality; it is a profound source of spirituality.
– "The Demon-Haunted World: Science as a Candle in the Dark," 1995

There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.
– "Pale Blue Dot: A Vision of the Human Future in Space," 1994

Every one of us is, in the cosmic perspective, precious.
– "Cosmos," 1980

The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of star stuff.
– "Cosmos," 1980

Exploration is in our nature. We began as wanderers, and we are wanderers still. We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars.
– "Cosmos," 1980

Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.
– "Pale Blue Dot: A Vision of the Human Future in Space," 1994

Every kid starts out as a natural-born scientist, and then we beat it out of them. A few trickle through the system with their wonder and enthusiasm for science intact.
– "Interview in Psychology Today," 1996

In meeting people, it's rare that what I'm impressed by is their intelligence. There's much more likelihood that what I'm impressed by is their compassion, their optimism, their sense of humor-things of that sort I find much more compelling.
– "Interview in Psychology Today," 1996

The visions we offer our children shape the future. It matters what those visions are. Often they become self-fulfilling prophecies. Dreams are maps.
– "Pale Blue Dot: A Vision of the Human Future in Space," 1994

Photo Credit: Jonatan Pie/ Unsplash