“Just as there are odors that dogs can smell and we cannot, as well as sounds that dogs can hear and we cannot, so too there are wavelengths of light we cannot see and flavors we cannot taste. Why then, given our brains wired the way they are, does the remark, "Perhaps there are thoughts we cannot think," surprise you?”

Fourth Mansions, Ch. 1, trans. E. Allison Peers (1961),<!-- Image Books --> p. 77
Interior Castle (1577)
Context: Just as we cannot stop the movement of the heavens, revolving as they do with such speed, so we cannot restrain our thought. And then we send all the faculties of the soul after it, thinking we are lost, and have misused the time that we are spending in the presence of God. Yet the soul may perhaps be wholly united with Him in the Mansions very near His presence, while thought remains in the outskirts of the castle, suffering the assaults of a thousand wild and venomous creatures and from this suffering winning merit. So this must not upset us, and we must not abandon the struggle, as the devil tries to make us do. Most of these trials and times of unrest come from the fact that we do not understand ourselves.

The Man in the High Castle (1962)

Source: Think Big (1996), p. 206

Miles "Pudge" Halter, pp. 220-221
Looking for Alaska (2005)

A Propos of Lady Chatterley's Lover (1929)
Context: We are today, as human beings, evolved and cultured far beyond the taboos which are inherent in our culture. This is a very important fact to realise. Probably, to the Crusaders, mere words were potent and evocative to a degree we can't realise. The evocative power of the so-called obscene words must have been very dangerous to the dim-minded, obscure, violent natures of the Middle Ages, and perhaps are still too strong for slow-minded, half-evoked lower natures today. But real culture makes us give to a word only those mental and imaginative reactions which belong to the mind, and saves us from violent and indiscriminate physical reactions which may wreck social decency. In the past, man was too weak-minded, or crude-minded, to contemplate his own physical body and physical functions, without getting all messed up with physical reactions that overpowered him. It is no longer so. Culture and civilisation have taught us to separate the reactions. We now know the act does not necessarily follow on the thought. In fact, thought and action, word and deed, are two separate forms of consciousness, two separate lives which we lead. We need, very sincerely, to keep a connection. But while we think, we do not act, and while we act we do not think. The great necessity is that we should act according to our thoughts, and think according to our acts. But while we are in thought we cannot really act, and while we are in action we cannot really think. The two conditions, of thought and action, are mutually exclusive. Yet they should be related in harmony.

Source: The Consolations of Philosophy (2000), Chapter II, Consolation For Not having Enough Money, p. 65.

Source: The Aquarian Conspiracy (1980), Chapter Twelve, Human Connections: Relationships Changing, p. 403