The atavistic urge toward danger persists and its satisfaction is called adventure.

One sees great things from the valley; only small things from the peak.

What one man can invent another can discover.

I learned to make my mind large, as the universe is large, so that there is room for paradoxes.

What one man can invent another can discover.

I am tormented with an everlasting itch for things remote. I love to sail forbidden seas and land on barbarous coasts.

True originality consists not in a new manner but in a new vision.

There are truths that prove their discoverers witless.

They are ill discoverers that think there is no land, when they can see nothing but sea.

When they shout “Long live progress,” always ask, “Progress of what?”

The unknown is the largest need of the intellect.

Science is a cemetery of dead ideas.

The eternal mystery of the world is its comprehensibility.