Unfortunately, it is much easier to shut one's eyes to good than to evil. Pain and sorrow knock at our doors more loudly than pleasure and happiness; and the prints of their heavy footsteps are less easily effaced.

Men can intoxicate themselves with ideas as effectually as with alcohol or with bang and produce, be dint of serious thinking, mental conditions hardly distinguishable from monomania.

There are some men who are counted great because they represent the actuality of their own age, and mirror it as it is. Such an one was Voltaire, of whom it was epigrammatically said: "he expressed everybody's thoughts better than anyone." But there are other men who attain greatness because they embody the potentiality of their own day and magically reflect the future. They express the thoughts which will be everybody's two or three centuries after them. Such as one was Descartes.

We are prone to see what lies behind our eyes, rather than what apprears before them.

Every great advance in natural knowledge has involved the absolute rejection of authority.

It is not who is right, but what is right, that is of importance.

Life is like walking along a crowded street--there always seem to be fewer obstacles to getting along on the opposite pavement--and yet, if one crosses over, matters are rarely mended.