But if humans can make new varieties of plants and animals, must not nature do so also? This related process is called natural selection. That life has changed fundamentally over the aeons is entirely clear from the alterations we have made in the beasts and vegetables during the short tenure of humans on Earth, and from the fossil evidence.

Carl Sagan

Carl Sagan

Profession: Astronomer
Nationality: American

Some suggestions for you :

Modern science has been a voyage into the unknown, with a lesson in humility waiting at every stop. Many passengers would rather have stayed home.

She had spent her career attempting to make contact with the most remote and alien of strangers, while in her own life she had made contact with hardly anyone at all.

I can find in my undergraduate classes, bright students who do not know that the stars rise and set at night, or even that the Sun is a star.

So far as I know, childbirth is generally painful in only one of the millions of species on Earth: human beings. This must be a consequence of the recent and continuing increase in cranial volume... Childbirth is painful because the evolution of the human skull has been spectacularly fast and recent.

The universe belongs to those who, at least to some degree, have figured it out.

The method of science is tried and true. It is not perfect, it's just the best we have. And to abandon it, with its skeptical protocols, is the pathway to a dark age.

A radio telescope works more like a light meter than a camera. You point it toward some fairly broad region of the sky, and it records how much energy, in a particular radio frequency, is coming down to Earth.

We are like butterflies who flutter for a day and think it is forever.

In any case, we do not advance the human cause by refusing to consider ideas that make us frightened.

Where we have strong emotions were liable to fool ourselves.

Fanatical ethnic or religious or national chauvinisms are a little difficult to maintain when we see our planet as a fragile blue crescent fading to become an inconspicuous point of light against the bastion and citadel of the stars.

The first two letters of the name Pluto are the initials of Percival Lowell. Its symbol is , a planetary monogram. But Lowell's lifelong love was the planet Mars. He was electrified by the announcement in 1877 by an Italian astronomer, Giovanni Schiaparelli, of canali on Mars.

We are privileged to live in, and if we are lucky to influence, one of the most critical epochs in the history of the human species.

The suppression of uncomfortable ideas may be common in religion and politics, but it is not the path to knowledge; it has no place in the endeavor of science.