Let us be grateful to the mirror for revealing to us our appearance only.

In fact, it is a farce to call any being virtuous 

whose virtues do not result 

from the exercise of its own reason.

All my life through, the new sights of Nature made me rejoice like a child.

Science cannot solve the ultimate mystery of nature. 

And that is because, in the last analysis, 

we ourselves are a part of the mystery that we are trying to solve.

Prejudices, 

it is well known, 

are most difficult to eradicate 

from the heart whose soil has never been loosened or fertilised by education; 

they grow firm there, 

firm as weeds among stones.

To raise new questions, 

new possibilities, 

to regard old problems from a new angle, 

requires creative imagination 

and marks real advance in science.

Character, in great and little things, means carrying through what you feel able to do.

All our knowledge has its origins in our perceptions.

In the landscape of extinction, 

precision is next to godliness.

It is the supreme art of the teacher 

to awaken joy 

in creative expression 

and knowledge.

To handle a language skilfully 

is to practice a kind of evocative sorcery.

What we need 

is not the will to believe, 

but the wish to find out.

No man's error becomes his own Law; 

nor obliges him to persist in it.

Dare to be true. 

Nothing can need a lie: 

a fault which needs it most, 

grows two thereby.

All we know is still infinitely less than all that remains unknown.