Hypotheses are the scaffolds which are erected in front of a building and removedd when the building is completed. They are indispensable to the worker; but the worker must not mistake the scaffolding for the building.

No one is willing to believe that adults too, like children, wander about this earth in a daze and, like children, do not know where they come from or where they are going, act as rarely as they do according to genuine motives, and are as thoroughly governed as they are by biscuits and cake and the rod.

Ye great teachers: listen to what you say!

Win for yourself that which your fathers have won.

Fortunately, we can take in only so much misfortune; what exceeds that limit either destroys us or leaves us indifferent.

Basic characteristics of an individual organism: to divide, to unite, to merge into the universal, to abide in the particular, to transform itself, to define itself, and as living things tend to appear under a thousand conditions, to arise and vanish, to solidify and melt, to freeze and flow, to expand and contract. Since these effects occur together, any or all may occur at the same moment.

Man is not born to solve the problem of the universe, but to find out what he has to do; and to restrain himself within the limits of his comprehension.