“Above all, it is necessary to recognize that knowledge cannot be pumped into human beings the way grease is forced into a machine. The individual may learn; he is not taught.”

Address to the British Association for the Advancement of Science (1898)
Context: No incident in my scientific career is more widely known than the part I took many years ago in certain psychic researches. Thirty years have passed since I published an account of experiments tending to show that outside our scientific knowledge there exists a Force exercised by intelligence differing from the ordinary intelligence common to mortals. This fact in my life is, of course, well understood by those who honored me with the invitation to become your president. Perhaps among my audience some may feel curious as to whether I shall speak out or be silent. I elect to speak, although briefly. … To ignore the subject would be an act of cowardice — an act of cowardice I feel no temptation to commit.
To stop short in any research that bids fair to widen the gates of knowledge, to recoil from fear of difficulty or adverse criticism, is to bring reproach on science. There is nothing for the investigator to do but to go straight on; "to explore up and down, inch by inch, with the taper his reason; "to follow the light wherever it may lead, even should it at times resemble a will-o'-the-wisp. I have nothing to retract. I adhere to my already published statements. Indeed, I might add much thereto. I regret only a certain crudity in those early expositions which, no doubt justly, militated against their acceptance by the scientific world. My own knowledge at that time scarcely extended beyond the fact that certain phenomena new to science had assuredly occurred, and were attested by my own sober senses and, better still, by automatic record. I was like some two-dimensional being who might stand at the singular point of a Riemann's surface, and thus find himself in infinitesimal and inexplicable contact with a plane of existence not his own.
I think I see a little farther now. I have glimpses of something like coherence among the strange elusive phenomena; of something like continuity between those unexplained forces and laws already known. This advance is largely due to the labors of another association, of which I have also this year the honor to be president — the Society for Psychical Research. And were I now introducing for the first time these inquiries to the world of science I should choose a starting point different from that of old. It would be well to begin with telepathy; with the fundamental law, as I believe it to be, that thoughts and images may be transferred from one mind to another without the agency of the recognized organs of sense — that knowledge may enter the human mind without being communicated in any hitherto known or recognized ways.

"Energy and Force" (Mar 28, 1873)

Jacob Leupold (1724); as cited in: Helmut Müller-Sievers (2012) The Cylinder: Kinematics of the Nineteenth Century. p. 146

Source: Giovanni Gentile: Philosopher of Fascism, (2001), p. 55

A Testament (1957)

A Poet's Advice (1958)
Context: Almost anybody can learn to think or believe or know, but not a single human being can be taught to feel …
the moment you feel, you're nobody-but-yourself.
To be nobody-but-yourself — in a world which is doing its best, night and day, to make you everybody else — means to fight the hardest battle which any human being can fight; and never stop fighting.

In Search of the Miraculous (1949)

Source: One Minute Nonsense (1992), p. 53

"Education for Independent Thought" in The New York Times, 5 October 1952. Reprinted in Ideas and Opinions (1954)
1950s
Context: It is not enough to teach a man a specialty. Through it he may become a kind of useful machine but not a harmoniously developed personality. It is essential that the student acquire an understanding of and a lively feeling for values. He must acquire a vivid sense of the beautiful and of the morally good. Otherwise he—with his specialized knowledge—more closely resembles a well-trained dog than a harmoniously developed person. He must learn to understand the motives of human beings, their illusions, and their sufferings in order to acquire a proper relationship to individual fellow-men and to the community. These precious things are conveyed to the younger generation through personal contact with those who teach, not—or at least not in the main—through textbooks. It is this that primarily constitutes and preserves culture. This is what I have in mind when I recommend the "humanities" as important, not just dry specialized knowledge in the fields of history and philosophy.