“The joy of discovery is certainly the liveliest that the mind of man can ever feel.”

The fact that knowledge endlessly recedes as the investigator is about to grasp it is what constitutes at the same time his torment and happiness.

If I had to define life in a single phrase, I should clearly express my thought of throwing into relief one characteristic which, in my opinion, sharply differentiates biological science. I should say: life is creation.

First causes are outside the realm of science.

The great experimental principle, then, is doubt, that philosophic doubt which leaves to the mind its freedom and initiative, and from which the virtues most valuable to investigators in physiology and medicine are derived.

A great discovery is a fact whose appearance in science gives rise to shining ideas, whose light dispels many obscurities and shows us new paths.

A discovery is generally an unforeseen relation not included in theory.

Well-observed facts, though brought to light by passing theories, will never die; they are the material on which alone the house of science will at last be built.

Particular facts are never scientific; only generalization can establish science.

Men who believe too firmly in their theories, do not believe enough in the theories of others. So these despisers of their fellows make experiments only to destroy a theory, instead of to seek the truth.

The true worth of an experimenter consists in his pursuing not only what he seeks in his experiment, but also what he did not seek.

The mental never influences the physical. It is always the physical that modifies the mental, and when we think that the mind is diseased, it is always an illusion.

Science increases our power in proportion as it lowers our pride.

When we meet a fact which contradicts a prevailing theory, we must accept the fact and abandon the theory, even when the theory is supported by great names and generally accepted.

The terrain is everything; the germ is nothing.

The experimenter who does not know what he is looking for will not understand what he finds.

The better educated we are and the more acquired information we have, the better prepared shall we find our minds for making great and fruitful discoveries.

If an historian be an unbeliever in all heroism, if he be a man who brings every thing down to the level of a common mediocrity, depend upon it, the truth is not found in such a writer.

Roll up your sleeves, set your mind to making history, and wage such a fight for liberty that the whole world will respect our sex.

All deep, earnest thinking is but the intrepid effort of the soul to keep the open independence of her sea, while the wildest winds of heaven and earth conspire to cast her on the treacherous, slavish shore.

Why do we spend years using up our bodies to nurture our minds with experience and find our minds turning then to our exhausted bodies for solace?

I think the greatest lesson I have just recently learned is how powerful the mind is, informing our decision making unknowingly.

Once I realized that the only thing I can actually control in this life is my own mind, how I choose to react, feel, and perceive, I felt immediately liberated.

Even if we love someone very much, at times it happens that we forget about it.

Liberty is not less a blessing, because oppression has so long darkened the mind that it can not appreciate it.