“The human understanding is moved by those things most which strike and enter the mind simultaneously and suddenly, and so fill the imagination; and then it feigns and supposes all other things to be somehow, though it cannot see how, similar to those few things by which it is surrounded.”

Source: Meditations (c. AD 121–180), Book VIII, 27

Source: The Character of Physical Law (1965), chapter 6, “Probability and Uncertainty — the Quantum Mechanical View of Nature,” p. 127-128

"The Imaginative Mind in Art" (1978)

Part I: Man and Nature, Ch. 1: Current Perplexities, pp. 4–5
1950s, New Hopes for a Changing World (1951)
Context: Consider MacArthur and his Republican supporters. So limited is his intelligence and his imagination that he is never puzzled for one moment. All we have to do is to go back to the days of the Opium War. After we have killed a sufficient number of millions of Chinese, the survivors among them will perceive our moral superiority and hail MacArthur as a saviour. But let us not be one-sided. Stalin, I should say, is equally simple- minded and equally out of date. He, too, believes that if his armies could occupy Britain and reduce us all to the economic level of Soviet peasants and the political level of convicts, we should hail him as a great deliverer and bless the day when we were freed from the shackles of democracy. One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision.

Professor Van Helsing to Dr. Seward
Dracula (1897)
Context: You reason well, and your wit is bold, but you are too prejudiced. You do not let your eyes see nor your ears hear, and that which is outside your daily life is not of account to you. Do you not think that there are things which you cannot understand, and yet which are, that some people see things that others cannot? But there are things old and new which must not be contemplated by men's eyes, because they know, or think they know, some things which other men have told them. Ah, it is the fault of our science that it wants to explain all, and if it explain not, then it says there is nothing to explain. But yet we see around us every day the growth of new beliefs, which think themselves new, and which are yet but the old, which pretend to be young, like the fine ladies at the opera.

This Business of Living (1935-1950)

Source: Dirk Gently's Holistic Detective Agency

VII, 30
Meditations (c. 121–180 AD), Book VII
Context: Direct thy attention to what is said. Let thy understanding enter into the things that are doing and the things which do them.

Source: Unaccustomed Earth