“You cannot teach a man anything, you can only help him to find it within himself.”
As quoted in How to Win Friends and Influence People (1935) by Dale Carnegie, p. 117; also paraphrased as "You cannot teach a man anything, you can only help him to find it for himself." Attributions are found as early as 1882.
Attributed
Source: Google Books link https://books.google.com/books?id=h70_AQAAMAAJ&pg=PA476&dq=You+cannot+teach+a+man+anything;+you+can+only+help+him+find+it+within+himself&hl=en&sa=X&ved=0CB0Q6AEwAGoVChMI39Gmss_gyAIVRNRjCh1Q2wGN#v=onepage&q=%22You%20cannot%20teach%22&f=false
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Galileo Galilei 70
Italian mathematician, physicist, philosopher and astronomer 1564–1642Related quotes

Lecture given in 1946 (Existentialism from Dostoyevsky to Sartre, ed. Walter Kaufman, Meridian Publishing Company, 1989;) http://www.marxists.org/reference/archive/sartre/works/exist/sartre.htm (1946)
Context: Dostoevsky once wrote: “If God did not exist, everything would be permitted”; and that, for existentialism, is the starting point. Everything is indeed permitted if God does not exist, and man is in consequence forlorn, for he cannot find anything to depend upon either within or outside himself. He discovers forthwith, that he is without excuse.

[2003, Survey of Metaphysics and Esoterism, World Wisdom, 220, 978-0-94153227-3]
Spiritual life, Happiness

शिक्षा (Education)
Context: In the fields of life there isn't any geometry. Here if whole is taken out from the whole then whole itself remains. Inside one is substance, inside atom is the world. Science cannot find everything and our psychological studies end within the darkness of intellect. This is why no teacher can teach.

Sat Chit Anand
Context: Nobody can teach you love. Love you have to find yourself, within your being, by raising your consciousness to higher levels. And when love comes, there is no question of responsibility. You do things because you enjoy doing them for the person you love. You are not obliging the person, you are not even wanting anything in return, not even gratitude. On the contrary, you are grateful that the person has allowed you to do something for him. It was your joy, sheer joy. Love knows nothing of responsibility. It does many things, it is very creative; it shares all that it has, but it is not a responsibility, remember. Responsibility is an ugly word in comparison to love. Love is natural. Responsibility is created by the cunning priests, politicians who want to dominate you in the name of God, in the name of the nation, in the name of family, in the name of religion -- any fiction will do. But they don't talk about love. On the contrary, they are all against love, because love is unable to be controlled by them. A man of love acts out of his own heart, not according to any moral code. A man of love will not join the army because it is his responsibility to fight for his nation. A man of love will say there are no nations, and there is no question of any fight.

Source: A Dream of John Ball (1886), Ch. 4: The Voice of John Ball
Context: Forsooth, he that waketh in hell and feeleth his heart fail him, shall have memory of the merry days of earth, and how that when his heart failed him there, he cried on his fellow, were it his wife or his son or his brother or his gossip or his brother sworn in arms, and how that his fellow heard him and came and they mourned together under the sun, till again they laughed together and were but half sorry between them. This shall he think on in hell, and cry on his fellow to help him, and shall find that therein is no help because there is no fellowship, but every man for himself.