A Stimulus (n.) never enters a dream in its real shape; it is replaced by another image bearing some affinity to it — but an affinity neither unique nor exclusive.
A Stimulus (n.) plays only a modest part in a dream: it accounts for one element, while other factors choose which memories it shall arouse.
A Stimulus (n.) besets the sleeper from every side, like the germs of life Mephistopheles complained of; each shakes a corner of the mind awake, and the mind is glad to sleep again.
A Stimulus (n.) can be traced in only a sliver of dreams, and even then it is never perceived as what it is but always misunderstood.
A Stimulus (n.) during sleep does not compel a dream; it may be ignored, felt 'through' sleep, or wake us — dreaming is only the fourth option, so the motive must lie elsewhere.
A Stimulus (n.) is present all night long, so if it caused dreams we would dream continuously of every organ; something must direct attention to it.
A Stimulus (n.) during sleep is interpreted like an illusion, with a motive: so that it shall not wake us and can be put to work for a wish.
A Stimulus (n.) only instigates a dream, as the crowning of a king occasioned Macbeth without explaining its greatness.