Only when I fall do I get up again.

First they ignore you, then they ridicule you, then they fight you, and then you win.

Whatever you are, be a good one.

The fact that the great scientist believed in flying machines was the one thing that encouraged us to begin our studies.

I discover myself on the verge of a usual mistake.

Weakness of attitude becomes weakness of character.

I long to accomplish a great and noble task; but it is my chief duty to accomplish small tasks as if they were great and noble

Yesterday is gone. Tomorrow has not yet come. We have only today. Let us begin.

People are capable, at any time in their lives, of doing what they dream of.

If the little bit you have is nothing special in itself, at least find a way of saying it that is a little bit special.

We should not give up and we should not allow the problem to defeat us.

They deem me mad because I will not sell my days for gold; and I deem them mad because they think my days have a price.

It's what you learn after you know it all that counts.

Know thyself.

Never let the future disturb you. You will meet it, if you have to, with the same weapons of reason which today arm you against the present.

Great work requires great and persistent effort for a long time. … Character has to be established through a thousand stumbles.

Every intention is a trigger for transformation.

I don't think necessity is the mother of invention. Invention ... arises directly from idleness, possibly also from laziness. To save oneself trouble.

The secret of genius is to carry the spirit of the child into old age, which means never losing your enthusiasm.

My optimism wears heavy boots and is loud.

He was a dreamer, a thinker, a speculative philosopher... or, as his wife would have it, an idiot.