No idea is conceived in our mind independent of our five senses [i.e., no idea is divinely inspired].

Heroism on command, senseless violence, and all the loathsome nonsense that goes by the name of patriotism - how passionately I hate them!

You can never solve a problem on the level on which it was created.

I think that only daring speculation can lead us further and not accumulation of facts.

All such action would cease if those powerful elemental forces were to cease stirring within us.

Everything has changed, except our way of thinking.

To my mind, to kill in war is not a whit better than to commit ordinary murder.