Plato

They certainly give very strange names to diseases.

No one is a friend to his friend who does not love in return.

To love rightly is to love what is orderly and beautiful in an educated and disciplined way.

Love is a serious mental disease.

At the touch of love everyone becomes a poet.

It is a common saying, and in everybody's mouth, that life is but a sojourn.

We can easily forgive a child who is afraid of the dark the real tragedy of life is when men are afraid of the light.

Life must be lived as play.

Justice in the life and conduct of the State is possible only as first it resides in the hearts and souls of the citizens.

I would fain grow old learning many things.

We do not learn and what we call learning is only a process of recollection.

Knowledge becomes evil if the aim be not virtuous.

Knowledge is true opinion.

Knowledge which is acquired under compulsion obtains no hold on the mind.

Knowledge without justice ought to be called cunning rather than wisdom.

Opinion is the medium between knowledge and ignorance.

The learning and knowledge that we have, is, at the most, but little compared with that of which we are ignorant.

Entire ignorance is not so terrible or extreme an evil, and is far from being the greatest of all too much cleverness and too much learning, accompanied with ill bringing-up, are far more fatal.

Human behavior flows from three main sources: desire, emotion, and knowledge.

Thinking: the talking of the soul with itself.