If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.
The reading of all good books is like a conversation with the finest minds of past centuries.
Except our own thoughts, there is nothing absolutely in our power.
All things in nature occur mathematically.
Each problem that I solved became a rule, which served afterwards to solve other problems.
It is not enough to have a good mind; the main thing is to use it well.
To live without philosophizing is in truth the same as keeping the eyes closed without attempting to open them; and the pleasure of seeing all that sight discloses is not to be compared with the satisfaction afforded by the discoveries of philosophy.It is only prudent never to place complete confidence in that by which we have even once been deceived.
An optimist may see a light where there is none, but why must the pessimist always run to blow it out?
The greatest minds are capable of the greatest vices as well as of the greatest virtues.
In order to improve the mind, we ought less to learn, than to contemplate.
If I had derived my existence from myself, I would not now doubt or want or lack anything at all; for I would have given myself all the perfections of which I have any idea. So I would be God.
Divide each difficulty into as many parts as is feasible and necessary to resolve it.
It is easy to hate and it is difficult to love. This is how the whole scheme of things works. All good things are difficult to achieve; and bad things are very easy to get.
Whenever anyone has offended me, I try to raise my soul so high that the offense cannot reach it.
Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has.
But the error of those who leant too much to the side of doubt, was not followed for any length of time, and that of the opposite party has been to some extent corrected by the doctrine that the senses are deceitful in many instances.
I am accustomed to sleep and in my dreams to imagine the same things that lunatics imagine when awake.
To know what people really think, pay regard to what they do, rather than what they say.
So blind is the curiosity by which mortals are possessed, that they often conduct their minds along unexplored routes, having no reason to hope for success, but merely being willing to risk the experiment of finding whether the truth they seek lies there.
The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once.