What goes up must come down.
No great discovery was ever made without a bold guess.
A man may imagine things that are false, but he can only understand things that are true.
They who search after the Philosopher's Stone [are] by their own rules obliged to a strict and religious life.
Plato is my friend — Aristotle is my friend — but my greatest friend is truth.
I have studied these things - you have not.
Lo que sabemos es una gota de agua; lo que ignoramos es un océano.
If I have seen further than others, it is by standing upon the shoulders of giants.
Yet one thing secures us what ever betide, the scriptures assures us that the Lord will provide.
Tact is the art of making a point without making an enemy.
Whence arises all that order and beauty we see in the world?
To explain all nature is too difficult a task for any one man or even for any one age.
No great discovery was ever made without a bold guess.
A man may imagine things that are false, but he can only understand things that are true.
And to every action there is always an equal and opposite or contrary, reaction.
Truth is ever to be found in the simplicity, and not in the multiplicity and confusion of things.
Nature is pleased with simplicity. And nature is no dummy.
Gravity explains the motions of the planets, but it cannot explain who sets the planets in motion.
What we know is a drop, what we don't know is an ocean.
Men build too many walls and not enough bridges.
Tact is the knack of making a point without making an enemy.
I can calculate the motion of heavenly bodies but not the madness of people.
If I have seen further it is by standing on the shoulders of Giants.